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Lactose Resistance, The Royal Society |
Milk has humans written all over it. We're the only mammals that drink milk into adulthood. And that's because we genetically re-engineered ourselves to do it.
For other mammals, and for lots of humans still, our body stops producing the enzyme that breaks lactose into usable nutrients once we're no longer kids. Without the enzyme (lactase), lactose stays a big glob of gunk that gives us indigestion.
Apparently, we liked milk so much that we just kept drinking it, and eventually we kept producing lactase for longer and longer into adulthood. We genetically modified ourselves through dairying practices, and it's the first example, or at least the best-documented, of cultural evolution. (Although the cultural evolution of seeing colors might be more interesting.)
Here's some more news on cultural transmission:
Study reveals lactose tolerance happened quickly in Europe
Sep 2020, phys.org
Some 3,000-year-old bones were found to NOT have the milk-drinking mutation. Medieval remains had the mutation in 60%, and modern people (from Northern and Central Europe) have it in 70-90%. This mutation happened way faster than anyone thought.
via Stony Brook University: Current Biology (2020). dx.doi.org/10.1016/j.cub.2020.08.033
Why some humans developed a taste for milk and some didn't
Sep 2020, phys.org
The trait of lactase persistence actually emerged independently at least three times; in northern Europeans, emanating from what is now Denmark, and in two geographically distinct African populations...involved different genetic changes, but to the same gene, lactose dehydrogenase, required for metabolising lactose into glucose.
via the University Of Cambridge: Yuval Itan et al. The Origins of Lactase Persistence in Europe, PLoS Computational Biology (2009). DOI: 10.1371/journal.pcbi.1000491
Ancient proteins help track early milk drinking in Africa
Jan 2021, phys.org
In Europeans, there is one main mutation linked to lactase persistence, but in different populations across Africa, there are as many as four. How did this come to be? The question has fascinated researchers for decades. How dairying and human biology co-evolved has remained largely mysterious despite decades of research.
via the Max Planck Society: Madeleine Bleasdale et al. Ancient proteins provide evidence of dairy consumption in eastern Africa, Nature Communications (2021). DOI: 10.1038/s41467-020-20682-3
Also:
Post Script:
Greater than the sum of our parts: The evolution of collective intelligence
Jun 2021, phys.org
All Brains Equal:
Dr. Taylor continued: "For example, a form of cognition currently viewed as a disorder, dyslexia, is shown to be a neurocognitive specialization whose nature in turn predicts that our species evolved in a highly variable environment. This concurs with the conclusions of many other disciplines including palaeoarchaeological evidence confirming that the crucible of our species' evolution was highly variable." -link
