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.