Motherhood Evolved

A female snake, frog or salamander doesn't care for her offspring; she just lays her eggs and goes on her way. She might even see some predator eating her eggs and just sit there as if nothing significant just happened.

When the eggs survive and the young reptiles or amphibians crawl out of them, these young creatures are almost immediately self-sufficient. This is so different with mammals and birds; we warm-blooded creatures come into the world completely helpless, so it's nice to know that our mothers do care, and hang around for as long as needed for us to become adults who can sort of take care of themselves. This is no coincidence, but a result of how evolution gave us big brains with the ability to learn, and adapt quickly to changing circumstances. What follows is one hypothesis about how we became the smartest creatures on the planet, and how motherly care among warm-blooded creatures plays a major role in that development.

Hundreds of millions of years ago, (almost) all animal life on Earth was cold-blooded. Being cold-blooded had the big advantage of being very energy-efficient because of not having the ability to regulate their body temperatures, but the equally big disadvantage that habitats were limited to places that were warm enough to stay active, and during the night they had no choice but to sleep. Around 270 million years ago the first warm-blooded creatures started to appear; their ability to regulate their body temperature gave them the huge advantage of being able to feed at night, when all the big bad reptiles were asleep. Also, the insects were asleep, which meant there was lots of easily available food to be found in the dark hours.

It's observed that warm-blooded mammals burn 10 times as much calories per gram of body-weight, as a cold-blooded animal; much of that extra energy is needed to be able to regulate the body temperature, but a great deal is also spent on the ability to learn. It's not a well known fact that mental labor costs at least as much energy as physical labor, but it does. To solve this problem of getting all the extra calories needed, one solution is to be smart, to be able to process information about the changing environment and to adapt to the changes much faster than would be possible through the very slow process of mutating genes.

Now reptiles and amphibians can learn, a little bit, much less than even the most lowly rat, but they can learn. The hypothesis is that mother nature cranked up this learning ability in mammals and birds by supercharging their nervous systems, growing their brains, so to speak. This is why mammals are the only creatures with a cortex on top of their reptilian brains, and this is why the cortex is the last to develop during growth. Mammals have evolved to be smart as adults by giving them the ability to learn, but relatively helpless as babies; their learning brain is the last to develop, and starts out as a blank sheet...

The process of learning is also very energy intensive, as "learning" entails a physical re-structuring of the neurons in the brain; the human connectome, the "wiring diagram" of the grey mass in our heads, is constantly changing, especially while growing up. We never loose the ability to learn new things, but ideas and opinions and behaviors that have been repeated over and over again do result in much stronger neural connections, which does make it harder to learn new things because old habits are in fact old and very strong neural connections in that connectome; it's harder to un-learn than to learn for that reason.

Because young mammals need to learn how to feed themselves, in mothers neurons were adapted. The strong instinct for self-care mas modified and re-purposed to take care of those kids; mothers now feel pain when the young cry and happiness when they're doing okay. A threat to those young feels like a threat to themselves, and so on. It's also believed that this is the basis from which all other strong social ties within a lot of mammal species evolved. They say that there's no stronger force in the universe than the love of a mother for her child; this claim might well be true, especially when we realize how instrumental the evolution of motherhood within mammalian species has been for the strong social cohesion that made us sit on top of every food-chain on the planet.

There are of course exceptions to the rule of this hypothesis; alligators, for example, do care for their young sometimes, and it's unknown if this is a form of convergent evolution or not. And birds are believed to have evolved from small dinosaurs that have independently evolved metabolisms similar to that of mammals. It's all just a hypothesis with a lot left to be proved yet, but it's a very plausible one. If all this peaked your interest, please watch this video (1 hour and 12 minutes) that explains all this, but also delves into what this means for things like morality and conscience;

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