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speciation would be very rare indeed. But it isn’t. Given that a single plant can produce millions of eggs and pollen grains, an improbable event eventually becomes probable.
a quarter of all species of flowering plants were formed via polyploidy.
a new polyploid species can arise in just two generations.
the Welsh groundsel represents a new species that arose in the last hundred years.
As Linnaeus proposed, our anatomy places us in the order Primates along with monkeys, apes, and lemurs, all sharing traits such as forward-facing eyes, fingernails, color vision, and opposable thumbs.
within the Hominoidea we are grouped with the great apes in the family Hominidae, sharing unique features like flattened fingernails, thirty-two teeth, enlarged ovaries, and prolonged parental care.
Molecular data derived from DNA and protein sequences confirms these relationships, and also tells us roughly when we diverged from our relatives.
we diverged from our joint common ancestor about seven million years ago.
we share 98.5 percent of our DNA sequence with chimps,
Sahelanthropus tchadensis,
between six and seven million years ago, right when molecular evidence tells us that our lineage diverged from that of chimps.
Orrorin tugenensis,
australopithecines,
One could not ask for a better transitional form between humans and ancient apes than Lucy.
our upright posture evolved long before our big brain.
In many respects A. afarensis is intermediate between the apelike and human morphology.
A. rudolfensis, appear so intermediate in brain size that scientists argue hotly about whether they should be called Homo or Australopithecus.
(Modern humans, for example, span a very wide range: between 1,000 and 2,000 cubic centimeters, which doesn’t, by the way, correlate with intelligence.)
The first unequivocally tool-using human was Homo habilis (figure 25), whose remains first appear about 2.5 million years ago.
These bumps raise the possibility—still far from certain—that habilis was the first species with spoken language.
H. erectus (“upright man”) holds the distinction of being the first hominin to leave Africa:
the brain size of erectus was nearly equal to that of modern humans.
(the chin is a hallmark of modern H. sapiens).
The species also seems responsible for one of the most momentous events in human cultural history: the control of fire.
Neanderthals ceremonially buried their dead: perhaps the first inkling of human religion.
about 60,000 years ago, every H. erectus population suddenly vanished and was replaced by fossils of “anatomically modern” H. sapiens, who had skeletons nearly identical to those of living humans.
Recent analysis of fossil wrist bones, however, do support H. floresiensis as a genuine species of hominin,
It’s always easier to document evolutionary change than to understand the forces behind it.
Lowly Origin,
the first tool appeared around the time that brains started getting larger.
Even without fossils, we have evidence of human evolution from comparative anatomy, embryology, our vestigial traits, and even biogeography.
We’ve learned of our fishlike embryos, our dead genes, our transitory fetal coat of hair, and our poor design, all testifying to our origins. The fossil record is really the icing on the cake.
There are over fourteen hundred novel genes expressed in humans but not in chimps.
The Mismeasure of Man,
Races (also called “subspecies” or “ecotypes”) are simply populations of a species that are both geographically separated and differ genetically in one or more traits.
The existence of different races in humans shows that our populations were geographically separated long enough to allow some genetic divergence to occur.
the cultural change can also produce genetic change.
The DNA data shows that, overall, genetic differences among human populations are minor.
The evolution of lactose tolerance is another splendid example of gene-culture coevolution.
It turns out that tolerant individuals must have produced, on average, 4 to 10 percent more offspring than those who were intolerant. That is pretty strong selection.
there is one mutant gene—an allele called CCR5-Δ32—that provides its carriers with strong protection against infection with the AIDS virus.
nearly every species has genetic variation to respond to nearly any form of selection.
with all these exalted powers—Man still bears in his bodily frame the indelible stamp of his lowly origin.
you can see fossils in any natural history museum,
Every fossil that we find, every DNA molecule that we sequence, every organ system that we dissect supports the idea that species evolved from common ancestors.
There is no dissent among serious biologists about the major claims of evolutionary theory—only about the details of how evolution occurred, and about the relative roles of various evolutionary mechanisms.
A science without controversy is a science without progress.
To these folks, evolution raises such profound questions of purpose, morality, and meaning that they just can’t accept it no matter how much evidence they see. It’s not that we evolved from apes that bothers them so much; it’s the emotional consequences of facing that fact. And unless we address those concerns, we won’t progress in making evolution a universally acknowledged truth.
Now, science cannot completely exclude the possibility of supernatural explanation. It is possible— though very unlikely—that our whole world is controlled by elves. But supernatural explanations like these are simply never needed: we manage to understand the natural world just fine using reason and materialism. Furthermore, supernatural explanations always mean the end of inquiry: that’s the way God wants it, end of story. Science, on the other hand, is never satisfied: our studies of the universe will continue until humans go extinct.
Godless: The Church of Liberalism,
