The Great Dying

Around 300 million years ago, a good part of a supercontinent covered the South Pole. Ice built up, draining the seas. A lot of earth’s oceans froze to the bottom causing an extinction for about 60% of living things. The period had sort of a bad start.

Amphibians and reptiles both got big and strong, the biggest guys on the block, and a lot of them survived. As life fought back, two important new reptile blood lines appeared. One line led to huge dinosaurs. The other eventually led to mammals. Shortly after they appeared, though, they faced a pretty serious threat.

By about 250 million years ago, a too-warm Earth released ocean gases poisonous to all living things. Estimates say 96% of life in the oceans and 70% of the vertebrates on land were wiped out by this extinction, called The Great Dying.   Life on Earth finally did recover but it may have taken ten MILLION more years for this to happen. No complete agreement exists on the cause of that massive catastrophe. Most now agree continent collisions caused massive volcanoes. Repeated and continuous volcanic eruptions kept so much soot in the air that the Earth’s surface got very little sunshine. The soot-filled air made breathing very, very difficult.

Enough of the two new lines – to dinosaurs and mammals – survived to avoid extinction. Dinosaurs are considered to be reptiles; they not in our direct evolutionary line. But those big, mean-looking scary animal cannot just be skipped!

Just for fun, before going back to that pre-mammal line evolution line being followed, take a break to follow those big, scary dinosaurs through their relatively short existence. After the Great Dying, dinosaurs spread out. They filled the extinction gaps. Although the first fossil remains were found in Tanzania, now on the east coast of Africa, dinosaur fossils have been found on every continent.

The word “dinosaur” means “terrible lizard” but they were not lizards. Dinosaurs make up a separate group of reptiles who generally, but not always, walked in an upright position. Fossils indicate a length of up to ten feet; those huge dinosaurs that seemed so dominating in movies did not show up until later. At this point, they were just another animal group trying to scratch out a living. Reproduction involved the male fertilized the eggs inside the female’s body.

Eventually, dinosaurs ruled, but dinosaurs were just one nightmare-maker. Even scarier were the flying reptiles, the first flying vertebrates. Some were as small as sparrows but some had a thirty-foot wingspan. Think of a flying reptile the size of a small airplane attacking you from the heavens. Clearly, they had no natural enemies, so these flying reptiles ruled the skies beginning about 200 million years ago. Interestingly enough, neither birds nor dinosaurs evolved from them. Dinosaurs had no natural enemies but, thank goodness, one did come from the sky. That meteorite impact 65 million years ago ended the reign of the dinosaur.

Now back to that led from reptiles to mammals. Like the first dinosaurs, these little animals were small, in all likelihood, they living in the ground, not on the ground. Before the Great Dying appeared, those little pre-mammals developed a remarkable trait: lactation. Lactation will be necessary for mammals to appear; the development of lactation at this time preceded the first mammals by at least 100,000 years.

The Story of Lactation

How scientists see lactation happening is a good story.

The little pre-mammals were no match for the bigger reptiles and amphibians so those terrified little animals probably sought shelter. They still laid eggs, eggs that did not have hard shells like chicken eggs but were rather a thin parchment. A problem with such thin parchment is drying out. Marsupials solve this with a pouch; the pouch may have been an intermediate step for mammals. The lactation secretion probably came from former hair glands on the female chest.

The secretion was not exactly like mother’s milk of today but did contain chemical precursors of lactose. In a Darwinian interpretation, then, the pre-mammals that provided the moisture and warmth and, eventually, the chemicals most useful in fighting disease were the ones who produced the most successful offspring. Those offspring produced offspring who would behave similarly. Eventually, warmth and moisture providers become dominant. So while those little pre-mammals snuck around for food (and avoid being food for bigger animals), they tried to keep their eggs warm, then moist, then healthy. And the fluid the fluid used to keep the eggs healthy would eventually become mothers’ milk. And, lactation and all, these little pre-mammals lived through the Great Dying.

Picture mammal; what do you see? Probably dogs, cats, humans or maybe elephants or tigers. Those first pre-mammals did not look like any of those; they were sort of an insignificant little blurb in the animal world. Our little ancestors played the role of a reptile’s snack.

So, on the journey from pre-mammal to mammal, lactation is already in place even though using it with a newborn will not happen for a while. Another major change in this transition: warm-blooded from cold-blooded. These first pre-mammals were, like reptiles, cold-blooded.

Cold-blooded animals generally spend a lot of time basking in the sun, not to get a tan but to warm the body. Hunting for food followed warming the body. So what are those little burrowing pre-mammals to do? During the day, they would be a likely target for dinner by the bigger reptiles. No time for a suntan.

That scary existence connects to the transition from cold to warm-blooded. Since showing up in daylight was suicidal, slowly but surely, generation after generation, their bodies invested energy into maintaining a constant temperature. Slowly their bodies developed more thermal insulation and a mechanism for temperature control. Both of these required a larger brain.

The environment of that time was not particularly helpful. Around 210 million years ago, that big Pangaea supercontinent begins to split. Changes were happening, not all for the good. Carbon dioxide levels were rising, much higher than they are now. The forests near the equator spread well northward, almost to the two poles. The oceans were becoming very warm.

Around 200 million years ago, an extinction raised havoc. The earth got too warm – much as it is doing today. Recent research indicates as much as 12,000 gigatons (a gigaton is one billion tons; each ton is 2000 pounds) of methane drifted up from the sea floor to the atmosphere. Too much heat did cause the extinction – and that is what is happening right now.

But the march from pre-mammal to mammal marched on to one final, giant transition step: live birth.

For animals still laying eggs, the very last layer surrounding the baby developing in the egg is a soft bag which will eventually become a shell. Remember, the eggs are getting smaller. For those eggs, that “sort of bag” allows for gas exchange to and from the egg, which is how the secretions got there.

The live birth step began with that special amniote egg that allowed the transition from amphibian to reptile. In the egg, the embryo lived in life-maintaining fluids surrounded by a tough tissue. Around that was more fluid and then the egg shell. That tough tissue transitioned into a unique organ, a different sort of a bag. The bag was called the placenta, and communication between the mother’s body and that bag was by way of the umbilical cord. This placenta belongs to the baby not the mother.

Some pretty careful studies have shown that the process which led to the internal placenta drew upon some ancient genes—changes, remember, are always based on something that happened in the evolutionary line earlier. The reptiles had provided that tough tissue surrounding the fertilized egg. With those ancient genes, particularly genes involving growth and metabolism as a starting place, a pathway into the membrane developed. The pathway allowed for the nutrients formerly provided inside the egg to be provided instead inside the mother, via an umbilical cord. By a combination of copying and merging those ancient genes in different manners, the transition was made. The placenta for all species is not the same, although they all seem to start under the control of the same gene structure.

A Review of Brain Development

Reaching back almost to the beginning, our brain uses a communication system found in jellyfish, first appearing 600 million years ago. Their nerves and the manner they send signals are similar to ours. Your brain relies heavily on structures found in the animals that preceded us. The first known animal, sponges, appear just before jellyfish. They basically had a more primitive form of the communication system found in jellyfish BUT our brain still uses part of their communication system. How that process evolved between the first multicellular organism and sponges is unknown since fossils are not available.

Worms are the simplest organisms to have a central nervous system, allowing them to exhibit more complex forms of behavior. Insects have a small but remarkable brain which can, for example, permit the cockroach to dart away as soon as it senses the moving air preceding a quickly descending human foot. The insect brain controls crawling, hopping, swimming, flying, burrowing, mating, and you-name-it.

An animal’s information system runs up the spine to the brain. Vertebrates, with that stiff spine, improve the protection of the information system. In early vertebrates, one part of the brain controlled behaviors that had happened again and again. Those automatic responses are sort of like cruise control on a car. A bird flies straight at your head. You do not stop and ponder, “Hmm. Should I duck?” No. Your conscious brain is too slow; a reflex established in antiquity makes you duck.

Science quarrels when the first brain appears, but the more important question is “What does the brain do?” Basically, it signals; it communicates; it directs traffic.

Without using the term “brain,” signaling began with life. From the beginning, cells had a communication system. Without one, how else could the DNA of the first bacteria direct the organism to make a copy of itself and then reproduce by splitting that copy off? Each of those steps, from no-life to life, from bacteria to eukaryotes, eukaryotes to multicellular, multicellular to jellyfish, required cells signaling one another. For sure, the brain was more organized when vertebrates had it at the end of a central nervous system. But communication among cells had to begin with life itself.

The amphibian transition from water to land made a big impact on the brain’s development. By this time, the brain had a midbrain and forebrain where brain functions for hearing and seeing in a higher and drier world sharpened. One part of the brain included responses like dominance and submission. Sudden movements, intimidating objects and brighter light changed visions centers. A possibly threatening or sight or sound causes us to instinctively turn our face and eyes in that direction.

As the finished reptile appears, the brain controls vital functions like heart rate, temperature, breathing, and balance. The brain, at that point, has a brain stem connected to two spheres (called the cerebellum.) This section helps with learning new motor behaviors, such as swinging a golf club.

In addition, most of science agrees that emotional centers also existed in the reptilian brain. Likely members include the instinct to fight or run which might also be called terror or anger. Instincts regarding sexual drives as well as parenting can be found here.

Dinosaurs, birds and mammals all followed reptiles. Each of those began with the same brain structure – the same brain structure as the reptiles. The human brain contains that section (often called reptilian) which still controls involuntary and instinctive behavior. Contrary to the arrogant beliefs of too many humans, the brain did not start over when homo sapiens arrived.

The Evolution of Emotions

Let’s summarize. To begin, in an initial step, the male does not wait until the female eggs were in water. Instead, like those adventurous placoderms before them, the male fertilizes the eggs while they are inside the female. With internal fertilization step complete, all the ingredients needed to create an image of the parents were together inside the female.

Slowly but surely, the reproduction-in-water issue was solved as a remarkable egg, called amniote, evolved. An interesting story. Let’s set the scene:

  • As water sites got further and further apart, the female did not just drop the eggs anywhere; instead, held the eggs inside longer.
  • Amphibians had a kind of tissue surrounding the yolk in the egg. The extra internal time toughened that tissue. Soon, as the embryo grew, the tissue surrounded it, and closed.
  • As that happened, fluids maintaining life stayed inside the now-enclosed tissue.
  • As time passed, the egg shell itself got more and more resilient. Inside the shell, the embryo’s tissue was surrounded by a fluid which collected waste and passed on air to the embryo.
  • That last amphibian step, egg-to-tadpole-to-frog, now happened inside the tissue.

Imagine how much time that took for the mutation-natural selection sequence to cause the change. This happened only because the female did not just jettison eggs and move on; if a site for laying the eggs was not available, the female held them in.

That was the amniotic egg which led to reptiles – animals that did NOT need to stay near water. Now the females laid the eggs on land. Reptiles of today include turtles, crocodiles, lizards, and snakes. Some still need water nearby; others live in the desert. The process that yielded reptiles was complete about 300 million years ago.

As the time clock moves from 1.2 billion years ago to 300 million years ago, from the first appearance of gender to our ancestor reptiles walking on land, how has the evolution of emotions progressed? Start with these sort of background statements.

The most valid animal emotional behavior data is anecdotal. Accurate reports regarding the emotions and behaviors of animals must come from observing, without interruption, animal behavior in their natural environments. Unfortunately, science does not have much respect for such information. Mark Bekoff, arguably the most trusted name in the area of animal emotions, explains that much more clearly and eloquently.

One anecdote, of course, should not lead to a firm decision; two independent reports with similar results tend to be eye-openers, but when report after report after report have a consistent theme, respect is called for. This “emotion” section will lean heavily on information based on observation and anecdotes. Thankfully, there are many scientists pursuing this line of research.

In earliest posts, some kind of special attraction – a mysterious force – seemed to have an impact on all events. In terms of emotion, attraction and cooperation were already seen. Clearly communication existed as well as some behaviors one would associate with a brain. What additional emotion-based research can be found from 1.2 billion to 300 million years ago?

About a half million years ago, about the time sponges appeared, the ancestors of those cherished lobster dinners, crustaceans, appeared.   One crustacean, the hermit crab, actually has no shell of their own. Instead, they find and live in abandoned shells of others. Research searching for hermit crab emotions unearthed two surprising emotional developments this early. First, the hermit crab reacts to pain, and second, the hermit has enough memory to avoid pain. Emotions and memory.

A little later, before the bony fish appeared, those ferocious placoderms provide fossil evidence of internal fertilization. The author of this Scientific American article writes,“The paired pelvic fins in placoderms permitted the males to deposit sperm into the females. This eventually gave rise to the genitalia and legs of tetrapods. And jaws may have originally evolved to help male fish grab a hold of females and stabilize them during mating, only later taking on the role of food pro­cessing. Sex, it seems, really did change everything.” This certainly appears to confirm that force of attraction and reinforce that if some action is rewarding, that action will be sought again and again.

Fish appeared just a little later. In most cases, fish lay eggs to reproduce. The female lays them; male comes by and fertilizes. But this is not impersonal. In most cases, the male is with the female as the eggs laid, immediately fertilizing them. The fish displayed various forms of protecting their young, including building walls. Here the two genders are working together after fertilization, indicating some sort of bond that holds them together. Examples of fairly elaborate nests out of the reach of predators abound. Having the male and female at the same location is not necessary; but many species apparently enjoy (or something) being together at that time. Attraction. Parenting. Being together. Protecting both the born and unborn. Do not believe people who say this did not begin until mammals.

A device that scared fish was inserted in a fish tank, immediately swimming from the feared object to escape. Next time, they were shown a bright light 10 seconds before the scary insertion. Well, over time fish learned to avoid the fearful event by leaving when the light turned on. Then, seven days went by with no light, no fear. On the eighth day, the light turned on. The fish immediately swam to escaped. So, at this point in the evolutionary process, the fish brain demonstrated hearing, fear, learning, and memory.

Bony fish, from which amphibians evolved, are in our evolutionary line. In about 20% of the specie, one of the parents holds the fertilized egg in its mouth, protecting the eggs from danger while waiting for the fry to hatch. That takes about a week. The story continues: In one specie, the father stays with the fry. If danger is near, the father swims to the fry and takes them in his mouth, holding them until danger is gone. What is seen here certainly seems like parenting, already tucked in the brain of some fish.

Here is a new emotion, branching out a little further. Generally, guppy females seek a male with bright orange coloring. However, when a female sees other females mating with a male with non-orange coloring, she will copy that behavior to also seek a male of similar coloring. Culture, seeking to conform to the group, the female is NOT following her own genetic drive but is responding to the behavior of others, as in “Monkey see. Monkey do.” Living in groups creates a whole new set of responses in the brain. Notice that this behavior is connected to parenting (seeking a mate) but has reached beyond parenting.

The female lays eggs; the male fertilizes, sometimes using internal fertilization. Somehow, they most communicate. They appear to choose to stay close. Why? Was it rewarding or maybe just the expectation of a reward? The no-contact technique was more convenient and much safer. That just provides predators a target twice as big! Does it not seem that something else made them seek one another?

The earlier speculative “automatic response” seems to fit here AND seems to be taking on more specific meaning. Something like the “anticipation of satisfaction” certainly seems to be going on. Even now for humans, the anticipation of satisfaction is a common behavior motivation. Catch that: not an actual satisfactory experience but instead being drawn to one another by the expectation of satisfaction.

Remember, these behaviors impact the structure of the DNA and the brain. Genders cooperating to allow internal fertilization certainly seems linked to emotional responses, stretching further the role of expectation of satisfaction in the mating process. Randomness followed by natural selection certainly is true; but from this perspective, it looks like developing emotions are taking a far bigger role in this evolutionary process than science has been willing to accept.

A substantial reproductive change occurred in this step. Usually, the egg (laid in the water) contains a not-yet-fully-developed amphibian. The animal’s DNA , though, then guides the transition of the newly-born to a land-dwelling amphibian.

Moving to Land: Amphibians

Amphibians evolved from the lobe-finned fish. Most of this change happened in shallow water. The bottom fins (those little sharp parts that help a fish navigate) were in pairs AND were supported by internal bones.

Environmentally, as the amphibians took charge, conditions were unique. Parts of what is now North America, Europe and Asia were near the equator. They were hot, wet, humid with and were hot, wet and humid with oxygen levels up to 31% (compared to 21% now.) The heat and extra oxygen had much to do with rapid growth, leading to enormous and dense swamps filled with mosses, ferns and giant trees. With six-foot long poisonous centipedes and dragonflies the size of a seagulls, the swamps sound quite unpleasant. However, where this dense vegetation once was, in North America and elsewhere, much later it decayed and became coal.

For amphibians, conditions could not have been more ideal.

The lobe-finned fish lived on plants or smaller fish in that very shallow water. Some was on land. Lobe finned fish to follow it, slowly but surely those four fins strengthened, eventually to be called legs. That transition might have taken 30 or 40 million years. An animal living in water has buoyancy for support; as the lobe-finned fish spent more time out of water, those muscles developed.

The fish had a sort of bony arch through which water flowed. The gills in fish have the capacity to pull oxygen out of the water then merge oxygen with nutrients to provide the fish energy. As more time on land strengthened that strong skeletal structure, those gills became pretty inefficient oxygen providers. That had to change. Eventually, that fish-structure shut down and was lost. As adults, the amphibian has primitive lungs and slimy sort of skin that actually pulls in oxygen through the skin. The gills are gone.

Aha! Your arms and legs have developed.

Water was high; amphibians fit in everywhere. Fossils have been found all over the globe. This event happened at a variety of sites at about the same time. Amphibian fossils have been found on every continent; so clearly they prospered.

Well, those ideal started to change as land masses inched toward each other and climate began to cool. Between 375 to 360 million years ago two extinctions occurred, almost ending this long story. Each lasted for a short (by evolution timing) period of about a quarter million years. But — the party ends. Some think the rapid growth of vegetation increased oxygen levels too much. The temperature dropped sharply. An extinction was hard on water-dwellers; perhaps 75% of all water species became extinct.

When the party ended, though, the amphibians were well underway. They needed water to lay their eggs; but they could also escape to land. The timing of the extinction was fortunate for amphibians. One good thing: those deadly and vicious placoderms ruling the seas became extinct. Most species of insects and plants joined the amphibians in survival.

Building a skeleton to hold up the amphibian on land was a key part of the transition. Surely the process of fins pushing around in shallow water and spending a more and more time in shallower water played a key role in the transition from fins to legs. Artifacts also show this was the start of internal fertilization. The article points that the process of the male holding on to penetrate the female strengthened the legs of both genders. Internal fertilization becomes a key part of the evolutionary process.

Catch that? Internal fertilization started? Just checking.

Amphibians, clearly in the evolutionary line that leads to us, vary in reproductive techniques. Some require penetration, some not. Frogs lay eggs but the male and females are in contact at the time of fertilization.

Amphibian reproductive process is a precursor to the next evolving specie, reptiles. Amphibians leave an egg that produces a fish-like animal which then grows to be an amphibian. For example, tadpoles leave the egg as a fish but eventually transition to frogs. As the newborn gets older, though, the DNA directs a slow transition to adulthood. In this process, the adult amphibian moves from breathing through gills to breathing with primitive lungs and through the skin. The amphibian still needs water nearby to be available but has learned to live for substantial periods on land.

Amphibian fossils suggest the transition from fish to amphibians was complete by about 340 million years ago. Those full-blown amphibians quickly became the big guy on Earth, the dominant specie. If the continents had just stayed separated with a lot of land covered with shallow water, the amphibians would still rule. But the earth underneath them foiled their dominance.

As the earth cooled, those water sites amphibians needed were getting further and further apart. As birth sites diminished, what was a female with eggs to lay going to do?   Next, I will summarize the steps upon which science seems to agree.

The Flexible Backbone Appears

As a very cold period ended, huge glaciers that had formed. Moving slowly, they scraping nutrients from the Earth’s crust to be absorbed by the oceans. This led to a buffet of oxygen-producing algae, providing the oceans with a dramatic increase in living organisms over the next fifty or so million years. Sea levels were very high – maybe a third of mile higher than they are today. Temperatures are mild; the first primitive plants moved onto land, probably a form of the green algae from the water. Over time, that green algae transitioned to very large ferns. Conditions were right for some important steps to take place.

About 600 million years ago, a little animal appeared that acted like a fish but looked like a worm. So what?   Remember the jellyfish with a strangely-arranged nervous system? Well – this little worm-like animal had a feature critical to our later development; a nervous system cord attached to a stiff but flexible backbone.

This little worm-like thing signals the development of an internal skeleton. At this point, no bones yet; instead, up the back, a stiff but flexible bone-like structure which has four flexible bony connections to the fins which will eventually become a bony spine with connections to the four limbs. Equally important, as the stiff part becomes our backbone, this step will carry the spinal cord to the brain. In time, segments of muscle, sort of like a string of pearls, wrap around that stiffened segmented part, providing protection.

Paying attention? Your backbone started to develop with a cord to the brain just like yours.

That worm-like animal evolved into a truly weird one – a fish without a jaw. Jawless fish, making their debut in both in ocean saltwater and freshwater lakes, had a fairly rigid backbone. That internal bone had a sort of upside down arch appearance; a like a couple of McDonalds arches.

The animals were ugly but their senses complex. They could sense sound and pitch and had eyes. Bottom feeders without a jaw, they had a sort of throat underneath them that sucked in water, took out the what was needed, and sent it back out through the gills. Actually, the stiff part was more like cartilage then bone; quite flexible. Some, but not all, scientists view jawless fish as the first vertebrates.

Paying attention? They could hear; they had eyes; and they had a throat.

All around them were bigger, stronger invertebrates who viewed the jawless fish as breakfast, dinner, or snack. In response, over time, these jawless fish developed a tough armored plate on the head. As bottom feeders, armor protected them from attacks from above. In time, that water intake hole moved around to the animal’s front leading to a jaw. These animals, by the way, were TRULY ugly. Say “hello” to the placoderms, not only ugly but nasty. They had an “open wide” mouth, sharp teeth, and were covered with protective armor – sort of an armored medieval warrior with weighting in at about a ton. Placoderms. In one bite one could cut a shark in half! Eventually they went extinct, but attention is needed; they were important contributors to the evolutionary line eventually leading to us. Well, at least humans did not inherit that big heavy plate on their heads.

An animal with a flexible backbone followed the placoderm.   The flexible bone is called cartilage, so (ta-daaaa) they are called the cartilage fish; the modern-day shark is the best-known cartilage fish. A your next visit to an aquarium (or being attacked by a shark) watch how smoothly they move through the water. The flexible backbone allows that movement.

When no one is looking, reach up and hold the divider inside your nose with your thumb and a finger. Move it around. That divider is cartilage, given to you before the cartilage fish spun off from placoderms. Another example: the sports page today reports on an athlete with a cartilage tear in the knee. All of us have cartilage bone junctions. And this will really shock you – but it is true: while you were in your mother’s womb, safe and warm, your earliest bones were cartilage. Then they changed to bones. So the cartilage fish took off on their own but before doing so made some contributions to you.

Besides the cartilage fish, a second group split-off from placoderms had backbones without that flexibility. The bones became hard so (ta-daaaa) they are called “bony” fish. By this point, all science agrees; these are vertebrates, the line that led to amphibians then reptiles and finally mammals and us.

Paying attention? Your bone structure has been added.

So while the cartilage fish went off their merry way, the bony fish line itself split into two parts. One group of bony fish remained in the deeper water.

The first group are what we still call “fish.” Between the oceans and fresh water lakes and rivers, as many as 25,000 fish species from the bony fish line are spread around the globe. For a Minnesota-born fisherman like the author, catching walleyes remains a pinnacle event—almost the reason for living.

The other group sought safety from those huge salt-water animals. The other pathway moved into shallower fresh water, in ponds, bays, and little streams caused by very high water levels on earth. This group needed a place where those huge saltwater predators could not go. This line was called the lobe finned fish because their structure was bones and muscles. Funny name; but this animal is in our direct evolutionary line.

OK, folks. Your ancestors moved out of the salt-water oceans to clean, fresh water. Feeling better?

Increased Complexity Appears

This is about how YOU got here, from that first moment of life in a very unpleasant ocean environment to the homo sapien that you are. Well, me too. It is indeed difficult to compare my body now to two extremely small organisms floating around in the ocean 1.2 billion years ago. But in this section, watch your body start to be put together.

With the availability of two genders, living organisms grew larger and more complex. Fossil remains for this next time period are limited. Why? Those developing organisms were soft. The time had not yet come when shells or bones were in place. Bones and shells will survive a billion years, but soft animals without either are hard to find after that long.   Science has cleverly found sound hints, though.   Most agree rapidly increased complexity was happening. By the time the first evidence is available, those DNA controlling lives probably had more complexity than the computer program that makes Google work.

Science does a good deal of information about the environment of this time. Early in this period, all the earth’s land masses had merged into the supercontinent Rodinia, with the equator going right through the middle. But those land masses started to separate, allowed big waterways to open between two big continental plates. Those ocean currents developed disruptive new routes which, apparently, helped the earth get colder.

Around 750 million years ago, that disruption came to a head. When a lot of water is consumed as ice by the glaciers, oceans get shallower. A substantial part of the ocean freezes to the bottom. Habitats are lost. Earth turned really cold, with ice as much as 2/3 of a mile thick covering most of the surface. Continued life could not be sustained in a substantial part of the oceans, but those little cells continued their march. Things warmed but, oops, around 720 years ago, the earth froze solid again. Life on earth was disrupted but not extinguished.

The first solid evidence of increased complexity, an apparent survivor of the last extinction, was finally found. The animal: a sponge. Some say “the lowly sponge” — not fair for a species that has now lived for more than half a billion years. Scientists believe that, over time, those early sponges greatly impacted the ocean by adding oxygen near the ocean’s bottom. With more oxygen available, new habitats and more life appear in deep water.

Sponges still do live at the ocean bottom, tightly attached to rocks. Their home is a structure with a lot of air-holes that absorb water. They are actually quite similar to the sponge used in kitchen or shower. As water moved in and out of the holes, the sponge absorbed nourishment . No food preparation for sponges; lunch comes to them.

Sponges sound simple but the complexity of their structure had gone well past that of those first bacteria or eukaryotes. One more important observation: although they did not have a nervous system, science recently has found they had the genes that were the precursor of the brain – your brain.

Not too much later, jellyfish appeared – yes, the same ones that can make swimming scary.   Sponges stay at a fixed spot; jellyfish search for food – and are still doing it here on Earth. What kind of more complex subroutines had the jellyfish assembled to survive so effectively?

Water supports them; bones had not yet evolved. Jellyfish are assembled symmetrically. The body plan, viewed from above, looks like an upside-down church bell. Down a center shaft water flows; the jellyfish has a subroutine to pull the food out for nourishment, much like the sponge does. The body, which is mostly water, has one multi-purpose opening where nutrients enters, waste leaves, and eggs go out or sperm comes in for reproduction.

The centralized brain had not yet arrived, but the jellyfish did have a pretty complex nerve net reaching up that central opening.   This nerve net guided where to swim for food – and which way was up or down. The nerve net also provided information about the water’s salt level, necessary because the mistake of swimming out of the salt water meant death for the jellyfish. The jellyfish also had eyes that could see; the signals when through the nerve net. To reproduce, the male releases the sperm and the females swims through it for fertilization.   An interesting cooperative system. And, as some unfortunate beach walkers and swimmers know, jellyfish can sting.

The goal is to show YOU your development process. Those little animals were already doing things we humans do. Think sexual reproduction. Sponges reproduce like hermaphrodites (both genders, one animal), just like the first eukaryote. The process was interesting. The sperm was first sent out into the seawater then drawn back into the animal to fertilize the egg. That process needed some sort of signals, some sort of communication between genders.

For the later-appearing jelly fish, the sperm-making male and egg-making female were separate. To reproduce, the eggs go into the stomach then out the mouth of the female jellyfish, followed by the same process from the male jellyfish. The jellyfish did not yet have a brain, per se, but did have a control system that worked like one. Some sort of cooperation, along with communication, had to exist.

A serious misconception is that emotion is unique only to the human brain. Our predecessors had emotions. An “angry sky” is not really angry; but an angry dog really is. Data that go way, way back confirm emotions can be tracked to the first primitive brains – and maybe even further.

Those first paragraphs describing the reproductive strategies of the sponge and jellyfish are based on scientific research by people who do this sort of thing as their life work. Science knows how they reproduce but an interesting question is, WHY do they reproduce? Science implicitly argues that animals go through the reproductive process so babies can be made. Maybe they are right – but – does it not make more sense that animals go through the reproductive process because of an emotional need or an emotional desire? Were reproduction steps painful, would male and female communicate to cause it to happen again? Of course not!

Cooperation is perhaps related to “being together” or “expectation of satisfaction.” Genders seemed attracted to one another. Cells can send signals; communication is possible. That “mysterious thing” seems to be hovering. Those reductionist pure scientists will not agree, but emotion was already underway for the line that led to you and me.

A Mysterious Force

Time for a pondering and thinking and speculating break. Since the appearance of gender seems so critical to that which followed, out of curiosity, suppose those critical first six steps are viewed backwards. To begin, though, remember the following.

Science has pretty much agreed on this: each little step depends on and draws from that which existed before. Close your eyes and try to picture these critical steps – from Big Bang to the appearance of separate genders.

Right after Big Bang, a mysterious force caused matter to seek other matter, thereby stopping the momentum to fly away in straight lines forever. Science calls it gravitational attraction.

Attraction. Keep that word in mind as the next step appears.

Life begins. Little, bitty single cells. Reproduce by making a copy of self and splitting into two. But a Nobel Prize was awarded to Max Delbruck in 1969 about the “…replication mechanisms in viruses.” An earlier Scientific American article by him has this summary: “Some fascinating experiments demonstrated that the tiny organisms which prey on bacteria employ a primitive kind of sexual reproduction.”

In other words, the makings of gender were there. About a billion years later they would separate but they were there — right from the beginning!

Look back. “Each step depends on and draws from that which existed before.” The makings of gender must have been in the noxious water from which life first appeared. Those “makings” would be different from the inorganic material around them; is that an attraction the put together the first DNA leading to first life?

Just pondering here.

In one of these new-fangled complex cells, over perhaps a half billion years, the material that made one gender separated from the material that made the other gender.

Two things to remember: The material from which the two genders was formed came from events that happened earlier. Some sort of force or pressure caused the material to separate from one another. Whatever was necessary to cause genders to separate after a long time in a single cell must have been drawn from those first complex cells.

Those first complex cells were built from material in single-celled organisms preceding them. In the other direction, gender differentiation was drawn from material in those first complex cells. Is that force or pressure causing gender separation part of this package? Did, by any chance, that unknown force have any connection to the merging of the two single-celled organism?

Life begins. Look back. The material appeared in first life had to contain what those two single-celled organisms needed to make that first complex cell. Look forward: First life had to separate from inorganic matter. That DNA assembled in water had to have material from which gender was assembled.

Once again there is a separation. Was that mysterious force separating genders involved in sorting the material needed for first life from inorganic matter?

Right after the Big Bang, a mysterious force caused matter to seek other matter, thereby stopping the momentum to fly away in straight lines forever. Science calls it gravitational attraction.

Think about it. “Attraction” is the key connecting word here, start to finish – at every step. Is that mysterious force already at work?

For this mysterious force to have that kind of impact, cells had to somehow communicate with one another. How could this mysterious force somehow have a way to communicate to guide cells to these dramatic changes?

Cells can communicate. Those very, very first DNA could not have done its job without some kind of electrical burst. Imagining a communication system is hard to accept – but then it is hard to imagine them having a complex DNA as well. The DNA guided each step; communication had to be there.


A snowball is flying at your face; you duck, instinctively, without thought. A little hummingbird can sing and fly, do a complex dance to attract a mate, build a nest, find food, and a lot more. Information about how and when to move the wings is signaled from the little bird’s brain. Communication. For DNA to work, a communication system had to exist. Is that how the material defining male and female slowly guided cells together in that chemical soup? Could there be a connection between matter seeking other matter and the elements of that soup sorting organic from inorganic through some kind of communication?

The key here: cells can signal one another; signals are sent from one part to the other. The idea of a mysterious force is not far-fetched.

Taking this approach, life’s beginning is just one stop in a continuous process. Life’s emergence is not a random event but just one stop in the transition from Big Bang to gender. Out of nothing, randomly, comes gender? No. Contemplation time seems to suggest a series of connected events, six events each unique in their own way. After all, each step depended on that which had already happened.

Science has the development of emotions and the brain starting much later than this. But that mysterious attraction certainly sounds like a prelude to emotions. If so, it is not only an emotion but the key emotion. And the fact that cells could communicate certainly sounds like the precursor of a brain which science declares begins much later.

The Mystery of Gender

Two types of single-celled bacteria merge to make a more complex cell.

After all, those bacteria were extremely efficient in passing along their genes to future generations. In their billion years or so of the Reign of the Prokaryotes, they had spread everywhere the oceans took them and even up onto some land masses. If the name of the game is successful reproduction, it sure looks like the prokaryotes had the upper hand. Nothing was broken; why fix it?

In the dog-eat-dog evolution that most people connect with Darwin’s theory, why would two successful and independent bacteria species give up their independence by cooperating to produce a new cell? Why not just keep reproducing their own stuff?

The cause is not explained by Darwin’s mutation followed by natural selection. Teamwork is the agreed-upon cause. Evidence shows that the new eukaryotic cell is clearly related to the two single-celled organisms. Maybe one species used the other as meal, but whatever caused it, symbiosis is the term used for a merger like this – an event that happens when one organism needed something the other organism had. At this time, the environment may be been nearing a Snowball Earth time. Maybe the two organisms needed this merger to stay alive.

What caused the two genders to separate within one of those more complex cells?

Science can tell you everything you want to know about inheritance of traits. But if there exists a scientific answer to the question, “How come the material making up the two genders separated in that cell?”, this researcher’s efforts failed to find it. However, one can find a lengthy list of why this SHOULD NOT have happened. Reasons:

  • Sexual reproduction makes the process less efficient. The result: it burns up more energy than just splitting into two new cells.
  • Look at the complication this adds to reproduction. Bacteria just split cell – and that’s it! The more complicated way: that egg floating around needs a mate.
  • That mates uses energy to get there. That energy might be better spent just splitting like the prokaryotes did.
  • Connecting with a mate brings in the idea of competition. Over time, females invest a lot of energy into being the most attractive so a male is drawn to them.
  • Two genders exist but only one reproduces. The other half does not reproduce.

My statistical side is screaming at me, “No. Genders were not necessary. The deck was somehow stacked to help guide that sorting!” What caused the two genders to become separate from one another?

“The deck was stacked.” How?  Science has pretty much agreed on this: each little step depends on and draws from that which existed before. Keep that mind through this review of the steps to here.


From one cell to many: Eukaryotes

At first, one cell included both gametes; a cell like that is called hermaphroditic, which means both the two genders still reside in the same membrane. They reproduced with hermaphroditic cells breeding with another. But before long, the two genders separated. One gender produced the egg and the other the produced sperm, just as humans do today. Soon the hermaphroditic cells pretty much disappeared and the single-sex cells dominated. Logic suggests a lot of reasons why that should not have happened:

  • Males compete with one another for the most desirable female with which to mate. Sometimes these competitions get pretty brutal.
  • The process the eukaryote goes through to reproduce is considerably more lengthy in time than is the prokaryotes process. Waste some time, fall behind.
  • And finally, the product of the reproductive process includes males and females. Males cannot reproduce. Thus the system is only half as effective as before.

Despite these, the event happened—and had it not happened, Earth would still have no living things but the single-celled prokaryotes.

The rate of evolutionary progress with the appearance of sexual reproduction increased dramatically. Looking backwards, sexual reproduction was a critical step leading to us. Period. Too many argue, “Well, it had to happen or we would not be here!” That statement assumes that the potential benefits are known by natural selection in advance. But the Darwinian process is randomness; pure, unadulterated randomness. Forecasting the future is not part of the process.

So two prokaryotes species game up their identity to make the eukaryotes but the eukaryotes were not gracious all. Their DNA called for ingesting food. To those new, bigger cells, bacteria were food. In fact, after a while a hole in the greedy eukaryotes membrane appeared, allowing the eukaryotes to swim along ingesting the bacteria. That hole eventually became our mouths. But the gobbling eukaryote was still a single cell.

In time, those special-duty single cells began to work together, sort of like “You make the soil, I’ll get the seeds, Al can plant them, and Louise will pick them.” They attached themselves to one another. But they retained their own DNA. Bigger cells had a competitive advantage. The problem: a single cell had a size limit.

Eventually, in order to get bigger, those the cooperating single-celled gave up their independence, in a one sense, to stay alive. They merged together, and became multicellular. The individual direction-centers were merged into one more complex DNA.

Multicellular means that now a lot of single cells, each with special functions, work together. As life becomes more complicated, so does the DNA at each step of the way. The DNA, remember, is the main library where all the directions are kept. As the organism becomes more complex, progress is maintained in the DNA.

Eukaryotes are the new kid on the block. So what, you say? Plants, fungi and animals will evolve from the new kid on the block. “Animals” include YOU!


Fossil evidence of this trip from single-celled to multicellular is scarce. Those first organisms were soft; a billion years or so later they do not leave any marks. However, scientists, working in their labs, have done a pretty good job of recreating this last transition. The evidence indicates the trip from single-celled to multicellular was a step-by-step process, a convergence, and not one big dramatic change.

In the absence of fossils, estimates of when this last step happened conflict. Based on evidence available suggest multicellular life appeared about 1.5 billion years ago, or 2.2 billion years after first life began. However, the appearance of two genders will indeed speed things up.