Usually, when we think of evolution, we typically think of a process which takes place over millennia. This time frame is very difficult to image
“Before humans, animal brains brains grew exponentially, but even more slowly, doubling about every thirty million years, starting about a half billion years ago. And before that, genomes seem to have doubled exponentially about every half billion years, starting about ten billion years ago.” (1).
The quote is showing that evolution is a long, cumulative process from natural selection which seems to only be able to be observed over a long period of time. It is a pity that it is hard for us to comprehend evolution because of the wide ranging explanations evolution provides.
However, evolution can be hard to grasp because it is not intuitive. It’s not intuitive that we share half our genes with a household banana or a fly.
But what if it were possible to track human evolution in a time frame of centuries rather than millennia? That’s just what Jonathan Prichard, Stanford Biologist did successfully tracked human evolution over the last couple centuries and has produced statistically significant differences between modern day Britain’s and those that successfully fought off the Romans some 2000 years ago.
To show, compared to their ancestors, present day Brits are taller, babies are born with bigger heads, and women’s hips are wider to support the bigger head babies, and as well as a built up lactose tolerance.
Between 5,000 – 10,000 years ago lactose tolerance emerged in the population and it’s presence within the human population has increased ever since. Lactase enzyme normally gets switched off during adulthood when we no longer survive on mother’s milk for nourishment; however, an allele kept the gene from switching off and allowed people to consume a diet rich in Dairy products.
The 3195 genes Prichard looked at in the sample of 10, 000 Britain’s he also found that there is a strong sexual preference for blonde hair and blue eyes, and height has also been a gene that was selected for. These differences make a difference in what we are since we are furthre down the evolutionary timeline.
- Robin Hanson “On exponential growth in the economy” – http://www.overcomingbias.com/2016/05/the-labor-from-factories-explosion.html