Chris Mooney has just blogged on a depressing new report that came out today that documents how the Bush administration puts politics before science.
Could test tube babies be revealing some of the hidden workings of evolution? It’s a definite possibility, judging from some recent reports about the balance of males and females.
Recently I’ve been trying to imagine a world without leaves. It’s not easy to do at this time of year, when the trees around my house turn my windows into green walls. But a paper published on-line today at the Proceedings of the National Academy of Science inspires some effort. A team of English scientists offer a look back at Earth some 400 million years ago, at a time before leaves had evolved. Plants had been growing on dry land for at least 75 million years, but they were little more than mosses and liverworts growing on damp ground, along with some primitive vascular plants with stems a few inches high. True leaves–flat blades of tissue that acted like natural solar panels–were pretty much nowhere to be found.
In 1970, the natural history illustrator Rudolph Zallingerpainted a picture of human evolution called “The March of Progress” in which a parade of hominids walked along from left to right, evolving from knuckle-walking ape to tall, spear-carrying Cro-Magnon. The picture is etched in our collective consciousness, making it possible for cartoonists to draw pictures like the one here safe in the knowledge that we’ll all get the joke. I had actually wanted to show Zallinger’s own picture, but, like others before me, I failed to find it on the web. I was inspired to hunt down the picture by the news today of the discovery of a strange new fossil of a hominid–an extinct relative of humans–that lived 900,000 years ago.
Our brains are huge, particularly if you take into consideration the relative size of our bodies. Generally, the proportion of brain to body is pretty tight among mammals. But the human brain is seven times bigger than what you’d predict from the size of our body. Six million years ago, hominid brains were about a third the size they are today, comparable to a chimp’s. So what accounts for the big boom? It would be flattering ourselves to say that the cause was something we are proud of–our ability to talk, or our gifts with tools. Certainly, our brains show signs of being adapted for these sorts of things (consider the language gene FOXP2). But those adaptations probably were little more than tinkerings with a brain that was already expanding thanks to other factors. And one of those factors may have been tricking our fellow hominid.