21 SEP 2011 by ideonexus
Are Humans Still Evolving?
Anybody who teaches human evolution is inevitably asked: Are we
still evolving? The examples of lactose tolerance and duplication of the
amylase gene show that selection has certainly acted within the last few
thousand years. But what about right now? It’s hard to give a good
answer. Certainly many types of selection that challenged our ancestors
no longer apply: improvements in nutrition, sanitation, and medical
care have done away with many diseases and conditions that killed our
ancestor... 1 
notes
notesCulture has removed many of the selective pressures from human survival, allowing harmful mutations to build up in the genepool; meanwhile, people living in third-world countries continue to experience selective pressures from droughts, famines, and disease.
21 SEP 2011 by ideonexus
Evolution of Lactose Tolerance
One case involves our ability to digest lactose, a sugar found in milk.
An enzyme called lactase breaks down this sugar into the more easily
absorbed sugars glucose and galactose. We are born with the ability to
digest milk, of course, for that’s always been the main food of infants.
But after we’re weaned, we gradually stop producing lactase. Eventually,
many of us entirely lose our ability to digest lactose, becoming “lactose
intolerant” and prone to diarrhea, bloating, and cramps a... 1 notes
notesSome groups of humans evolved the ability to digest milk beyond infancy as their societies domesticated cows.
