More from Ann Gauger on why humans didn’t happen the way Darwin said
|July 9, 2012||Posted by News under Human evolution, Intelligent Design, News|
In Science and Human Origins, Ann Gauger asks some key questions about how human beings got to be the way we are:
So Much to Do, So Little Time
For the purposes of my argument, I don’t intend to argue that H. erectus was or was not the first human being, or is directly part of our lineage. Instead, I want to focus on the anatomical changes that must be accomplished to go from A. afarensis to H. erectus. Regardless of whether or not other transitional hominins are found, these are the kinds of anatomical changes that must have occurred.
For a “radical transformation” of this kind to have happened by strictly neo-Darwinian means, as Hawks et al. imply, then some combination of mutation, genetic drift, and natural selection must be capable of producing the change. But “shifting the adaptive complex” to the new H. erectus anatomy would require reorganizing multiple anatomical structures, the kind of thing likely to require multiple specific mutations.
Two questions then arise: (1) How many mutations would it take to turn an australopithecine species into a Homo erectus? And (2) If there are only one and a half million years between A. afarensis and H. erectus, can neo-Darwinism produce the necessary changes in the time allotted? How many mutations would it take?
Bramble and Lieberman13 count sixteen features of the human body that first appear in H. erectus or H. sapiens. These features are necessary to stabilize the head, permit counter-rotation of the torso with the head and hips, stabilize the trunk, absorb shock and transfer energy during running. Many of these changes must occur together to be of any benefit.
Is there enough time to get sixteen anatomical changes by a neo- Darwinian process? Each of these new features probably required multiple mutations. Getting a feature that requires six neutral mutations is the limit of what bacteria can produce. For primates (e.g., monkeys, apes and humans) the limit is much more severe. Because of much smaller effective population sizes (an estimated ten thousand for humans instead of a billion for bacteria) and longer generation times (fifteen to twenty years per generation for humans vs. a thousand generations per year for bacteria), it would take a very long time for even a single beneficial mutation to appear and become fixed in a human population.
You don’t have to take my word for it. In 2007, Durrett and Schmidt estimated in the journal Genetics that for a single mutation to occur in a nucleotide-binding site and be fixed in a primate lineage would require a waiting time of six million years. The same authors later estimated it would take 216 million years for the binding site to acquire two mutations, if the first mutation was neutral in its effect.
But six million years is the entire time allotted for the transition from our last common ancestor with chimps to us according to the standard evolutionary timescale. Two hundred and sixteen million years takes us back to the Triassic, when the very first mammals appeared. One or two mutations simply aren’t sufficient to produce the necessary changes— sixteen anatomical features—in the time available. At most, a new binding site might affect the regulation of one or two genes. Durrett and Schmidt acknowledge the problem, and suggest that it can be overcome because there are an estimated 20,000 genes evolving independently, many of which might benefit from mutation(s) in their regulatory regions.
This is unreasonable. … (pp. 23-25)
(Yuh. People have said it about Darwinism before: This is unreasonable.)
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