Evolution is easier than we think, and one great way to see why is to look at what we know about protein evolution. Proteins have been evolving on our planet for about 4 billion years. Their appearance almost certainly precedes the beginning of life itself. We still don't know how the whole thing got off the ground, but once the stage was set (in living cells), evolution began exploring Protein Space.

We humans think we're pretty special. Here's Hamlet, in the speech that gave this blog its name: Kemble in the role of Hamlet. Courtesy of Wellcome Images.

A truly human-specific gene, not merely a human-specific version of an animal gene or a mammal gene or a primate gene — that is something particularly interesting.

Human evolution has been in the news quite a lot recently. New genetic data suggest that ancient humans included both Neanderthals and Denisovans, which colonized different parts of the world but subsequently interbred with so-called modern humans and left telltale traces of this history in the genomes of living humans.

Genetic hitchhiking is thought to be an inevitable result of strong positive selection in a population. The basic idea is that if a particular gene is strongly selected for (as opposed to selected against), then the chunk of the genome that carries that gene will become very common in the population.

The next post will discuss recent evidence for genetic hitchhiking in humans. So, what do we mean when we say that genes can hitchhike? To make sense of this phenomenon, we first need to review chromosomes and sexual reproduction. Most people know that sexual reproduction creates offspring that are genetically distinct from both of the their parents.

Not surprisingly, Hamlet weighed in on the nature vs. nurture question, at least once. It is certainly true that "the stamp of one defect" can wreak havoc on the scale that Hamlet describes, and whether the result is a debilitating physical limitation or damage to "the pales and forts of reason," the outcome is tragic by any measure.

In the cartoon version of evolution that is often employed by critics of the theory, a new protein (B) can arise from an ancestral version (A) by stepwise evolution only if each of the intermediates between A and B are functional in some way (or at least not harmful). This sounds reasonable enough, and it's a good starting point for basic evolutionary reasoning.

"The Selfish Gene." "Selfish DNA." Oh, how such phrases can get people bent out of shape.  Stephen Jay Gould hated such talk (see a little book called The Panda's Thumb ), and Richard Dawkins devoted more time to answering critics of his use of the term 'selfish' than should have been necessary.

Three weeks ago, I went to the Cornerstone Music Festival with my two oldest kids. For the second year, I was an invited speaker in the festival's excellent seminar program. This year, my two series were entitled "Alien Worlds" and "Zombies on Jeopardy" – exploring extreme biology and human nature, respectively. It was fun, if a little too hot for a day or so. At one point, I was discussing human intelligence and its genetic underpinnings.