After my public lectures on evolution, someone in the audience asks, "Are we still evolving?" People want to know if humans are getting taller, smarter, better looking or more athletic. My answer is truthful but 1: We're almost certainly evolving, but we don't know in what 2 or how fast.
We've seen some evolution in our species over the past few millennia, but it was detected by reconstructing history from DNA sequences. For example, we know that during the past 10,000 years, several populations of humans — those keeping sheep, cows or goats for milk— gained the ability to digest dairy products. This quality was 3 in our earlier ancestors who, after babyhood, never encountered milk. And in the past 3,000 years, Tibetans have acquired 4 adaptations that allowed them to develop well in their high-altitude, low-oxygen home. But these well-documented changes are limited to particular populations, so the 5 for recent evolution of our entire species, remains not much.
The authors of "Evolving Ourselves" 6. Not only, they claim, are we evolving faster than ever, but we're doing it to ourselves. Juan Enriquez and Steve Gullans argue that humans have 7 evolution — not just in our own species but virtually in all species: "For better or worse, we are increasingly in charge. We are the primary drivers of 8. We will directly and indirectly determine what lives, what dies, where, and when. We are in a different phase of evolution: the future of life is now 9."
According to the authors, we've replaced natural selection with what they call "10selection." Overfishing, for example, has reduced the average size of many fish species, for taking the biggest fishes is 11 those smaller fishes.
Yet while there's no doubt that we're changing the planet, the claim that we're completely changing evolution on the planet 12. Let's take those fish that are evolving to reproduce smaller and younger for example. This 13 has been documented in many species that we eat, but this is just a minuscule fraction (极小的一部分) of the 30,000 known species of fish.
The authors speak with 14 assurance about how our species is evolving in response to nearly everything. When they claim, for example, our ingestion (摄取) of drugs and exposure to chemicals mean that "our children's brains are evolving fast," they are abusing (滥用) the word "15." Our children's brains may be changing fast in response to the new pharmacological (药理学的) environment, but change alone is not evolution.
