Evolution — BIOLOGY STD 12 Science — Question

Some scientists have been studying this aspect of human evolution and have come with interesting observations which suggest the evolution is indeed taking place in modern humans. Some of the observations are as follows:

• Human evolution has accelerated since the discovery of farming about 10,000 years ago. There is substantial genetic difference between hunter gatherers and current humans.
• Human reproductive period has prolonged than it was 10,000 years ago. Earlier, the average life expectancy of human beings was about 30 years which is now more than double.
• Lactase persistence into adulthood is another sign of human evolution. All other mammals develop lactose intolerance because young ones are weaned away from mother’s milk after a certain age. Unlike humans; other mammals do not have the facility to consume other mammal’s milk. But human beings consume milk throughout their life because they get it from domesticated animals.
• Humans have also developed resistance to many infectious diseases. This is another sign of evolution.

However, evolution of modern humans cannot happen through geographical isolation because modern means of transport has blurred geographical boundaries. But evolution can happen because of genetic drift.