I Mammal

I enjoy reading history books, though it typically leaves me feeling infinitely small in the zeitgeist of human history aka the universe. There's been approximately 108 billion humans on this Earth (according to Chat GPT), and a number several magnitudes greater of total mammals (Chat GPT refused to get specific). Since synapsids broke off from reptiles and started on the evolutionary high way to developing LLMs (Dimetrodon isn't a dinosaur, but actually my great-grandpa?) there have been generations and radiations of so many layers and layers of creatures throughout the epochs that eventually gave us humans and golden retrievers and elephants without scrotums.

I found Liam Drew's I, Mammal: The Story of What Makes Us Mammals endlessly fascinating as he took me through the stages of evolution that led to nipples and middle ears and brains. Every time he explained how one of our mammalian traits could have developed - like hearing, and being able to survive out of water without oxygen - it made so much sense. Like, well, yeah I can see why that trait led to a higher success rate than other animals without it.

There were also lots of good titbits of a lighter nature. Like, apparently sperm were first observed by the person who invented the microscope. He didn't even let anyone else have a go first.

The chemistry of genes and hormones also was insightful. Apparently in one experiment with rats - who usually press a lever to be rewarded with food - were given a lever that resulted in baby rat pups being pushed out the chute. All the rats did not press this lever, except the group that they dosed with oxytocin triggering hormones and those rats pumped that lever until they had twenty babies at their feet. That explained a lot.

While I now feel even more miniscule, I do feel less like I am at the top of an evolutionary tree, or even a leaf on a branch. On timescales of millions of years I'm basically overlapping Napoleon in comparison to Dimetrodon. I am essentially background noise.