WASHINGTON -- This week a 47 million-year-old fossil was put on display at New York's American Museum of Natural History. Scientists accorded the event enormous attention, as did the press. The creature may be related to us, though it looks like a cat, not a chimpanzee, and certainly nothing like your mother or father or even one of your more eccentric aunts or uncles. Evolutionists tell us that of all the creatures known to science we humans are most closely related to chimpanzees.
That is not the whole story, of course. According to a very fine book that I have been reading, Why Evolution Is True by Jerry A. Coyne, an evolutionary biologist at the University of Chicago, mankind can be traced back over three billion years to our most distant relatives, self-replicating molecules. The fossil unveiled at the American Museum of Natural History is a relative newcomer, but she (the creature was a young female) has cleared up a debate among scientists. Anthropologists have been pretty certain that we evolved from ape-like ancestors, but they have been divided on precisely which one. There were two, the family Tarsiidae -- whose descendants, the tarsiers, are jungle creatures now living in Asia -- and the family Adapidae, who were precursors of the lemur of Madagascar.
Scientists base their speculations on fossils that are rarely complete. Some scientists have extrapolated our ancestors from as little evidence as a tooth. The lucky ones have had a jawbone or a rib or some other skeletal fragment. This week's fossil displayed in New York is a complete skeleton, except for a missing lower leg. From it evidence mounts that our ancestor is the adapidae, the precursor of the lemur. "Lemur advocates will be delighted," Tim White, a California paleontologist, is quoted as saying in the Wall Street Journal, "but tarsier advocates will be underwhelmed." Scientists are given to such disputes, and then there are the creationists who doubt we have any animal ancestors whatsoever. Let the debate continue.
What I have found fascinating in Coyne's book is how very old the earth is. Some of his evidence comes from fossils and measurements of the radioactivity in the layers of stone that harbors the fossils. The radioactivity gives us a good idea of the stone's age, and the progression of the fossils gives us an idea of their steady development.
Scientists, by dating old rocks, have established that the earth is 4.3 billion years old. The earliest fossils, those being photosynthetic bacteria, trace life on the planet beginning about 3.5 billion years ago. Around 600 million years ago multi-celled organisms appeared, for instance, worms and jellyfish. Then came terrestrial plants and four-legged animals about 400 million years ago. Mammals did not show up until 250 million years ago, and birds can be found in fossil form dating from 50 million years ago.
Coyne writes that "Humans are newcomers on the scene -- our lineage branches off from that of other primates only about 7 million years ago, the merest sliver of time." Then just over four decades ago Barack Obama was born, and just over six decades ago Newt Gingrich.
Coyne and other evolutionary biologists have had their theories fortified by the ability, starting three decades back, to sequence the genomes of various species and discover genes shared by related species, some that still work, some that do not thus allowing us to go our merry way from, say, our relative the chimpanzee. The key to this process, scientists say, is natural selection. There are good genes that help us survive and not-so-good genes that deny those who carry them the possibility of survival.
Now creationists find all this highly dubious, but for me the information has come as a great relief. The good news is that human beings adapt. We have survived, according to my reading of Coyne, for about 60,000 years, adapting to all sorts of challenges, climate changes, dietary changes, plagues, and other such unwelcome happenstances. The present hullabaloo over global warming is much ado about nothing. Let the climate change, the species Homo sapiens has survived 60 millennia. There is no reason for the Obama Administration to tamper with the automobile market. We can survive carbon in the atmosphere and have since the last weak-gened member of Homo erectus wobbled off. Unfortunately it is unlikely that the automobile industry can survive politicians designing our cars, taxing our gasoline, and supplying us with tiny vehicles that few Americans want to buy.
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