Environment dictates the evolution of animals. Whales lost their legs as they moved full time to water. But surely humans who have tailored the environment to their needs (AC, clothes, beds, roads, desk jobs, etc. etc.) must evolve less fast than animals?
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| Charles Darwin, the evolution theorist |
Well, no, on the contrary, humans are evolving genetically faster than previously thought, especially in
the last 40,000 years, with some studies suggesting an acceleration 10 to 100 times faster than the long-term average,
driven by factors like agriculture, larger populations, diseases, and
migration, leading to adaptations in immunity, diet (like lactose
tolerance), and skin color. While significant changes usually take
millennia, modern humans show rapid
genetic shifts in recent history due
to these environmental pressures and cultural developments.
"In the volcanic bedrock of the Andes, arsenic is naturally abundant and
leaches into the drinking water. The dangers it poses are well known:
inorganic arsenic is associated with cancers, skin lesions, heart
disease, diabetes and infant mortality in other populations.
But the
biochemistry of Andeans has evolved to efficiently metabolize this
notoriously toxic substance. Populations in Bolivia—along with groups in
Argentina and Chile—have evolved variants around the gene AS3MT, which makes enzymes that break down arsenic in the liver"
Increased Rate:
Studies indicate human evolution sped up significantly after
agriculture began, with selection pressures increasing dramatically in
the last 5,000 to 80,000 years. Selection means who gets to pair with a partner and produce a large brood.
It was considered preferable for a man to be taller than his woman partner: short men and tall women did not find partners, and the different in height and muscle bulk between men and women increased. There was very little different in neolithic times, so much so that paleontologists/archeologists who uncovered bones from these humans often mistook the remains for those of men, because the women's measurements were so similar.
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| Ice Age Dwellers, by Hans von Kraemer |
Gene Changes:
About 7% of the human genome shows signs of recent,
rapid evolution,
affecting traits like metabolism, immunity, and neural function.
Agriculture & Diet: New food sources (like dairy) led to adaptations such as
lactose tolerance in some populations.
Population Growth & Density: Larger, concentrated populations increased the rate of new mutations and facilitated the spread of certain genes.
 |
| Our genetic material (DNA) |
Disease & Environment:
More virulent diseases and different climates (e.g., colder regions)
drove rapid selection for advantageous genes, like those influencing fat
distribution.
Migration: Spreading into new environments led to
adaptations for local conditions, like skin and eye color changes. There was less pressure for humans in cold climates to have their pigmentation protect them from the sun, and blond hair and blue eyes appeared.
In
essence, human evolution hasn't stopped; it's been accelerating, fueled
by our own cultural and technological advancements creating new
selective pressures.
In
essence, human evolution hasn't stopped;
it's been accelerating, fueled
by our own cultural and technological advancements creating new
selective pressures.
