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.