Top critical review
Reviewed in the United States on February 2, 2018
First of all, I want to say that Gregg Braden's book "Human by Design" was well-written and well-researched, and it was an enjoyable read. However, his conclusion that human beings are a singular species is simply untenable. There certainly are gaps and flaws in orthodox Darwinism, as the originator of the theory of natural selection freely admits. However, it is abundantly clear from the archeological record that primitive species die out and are replaced by more advanced species over time. There are two possibilities: 1) Primitive species evolve into more advanced species through a steady process of genetic mutation (with natural selection choosing winners over losers), or 2) advanced species simply pop into existence. It is apparent that Mr. Braden believes that fully modern humans simply popped into existence approximately 200,000 years ago as a result of two "chimpanzee chromosomes" fusing into a single "human chromosome 2." In other words, the human species does NOT belong to the tree of life, but is specially-created standalone species that was intelligently designed.
Now it turns out that genetic mutations are occasionally accelerated for unknown reasons and significant changes sometimes occur over short periods of time, producing fossil gaps in the archeological record. However, the presence of gaps does not invalidate the conclusion that genetic mutation produces new species. All that is needed to produce a new species is to have one small population be separated from the main population and having to survive under stressful environmental conditions. It must be stressed that DNA is NOT a digital blueprint of a complete organism, but rather an instruction set on how to MAKE an organism utilizing highly-nonlinear processes and sophisticated feedback mechanisms that are not completely understood. Thus, making a simple modification to one gene can produce a drastic change to the entire organism. Modifying a particular gene belonging to a flying insect can produce an extra pair of wings (this has actually been demonstrated in the lab). If two sets of wings confers a survival advantage (or at least doesn't result in a dis-advantage) then the extra set of wings will appear in the offspring. Nobody "designed" the extra pair of wings..
Getting back to the "Human by Design", the author proposes that separates humans from other apes is the sudden fusion of two "chimpanzee chromosomes." Well, let's see how that may have happened. First off, let's all agree that humans didn't evolve from chimpanzees, and propose instead that some other pre-human ape-like species existed which had 48 chromosomes. At some point in time, an egg from one of these creatures was fertilized having only 46 chromosomes. After 9 months or so, a fully-human baby popped out of her uterus. How could that singular human baby have survived and produced more 46-chromosome offspring? That scenario is completely untenable.
There are two other possible ways of producing 46-chromosome humans without relying on evolution (mutation and natural selection):
1) An advanced alien civilization came to Earth, looked around and saw a bunch of 48-chromosome apes living in Africa. So these aliens decided to take the genetic material from these apes and manufacture a 46-chromosome version in their genetics lab. Some readers may find this to be a plausible scenario, but I think it evades the question of how the advanced aliens who created us came about. Did another alien civilization create THEM? It seems like there must be aliens all the way down in order for this to play out.
2) The other way an instantaneous act of human creation could have come about is found in the book of Genesis, where the raw material used to form the first humans wasn't "chimpanzee DNA" but just plain old dirt. Whenever there's a mystery that science cannot solve, it's awfully tempting to fall back to the argument that God (or some other super-intelligent and powerful being) did it.
In conclusion, "Human by Design" does expose a mystery, but the conclusion that we're the product of intelligent design is simply untenable. There are a lot more losers than winners in the genetic lottery, just as there are a lot more losers than winners in any lottery. (It's an unfortunate fact that about 50% of fertilized human eggs fail to develop for natural reasons). Just like you only see pictures of lottery winners in newspapers and never the losers, the losers of the genetic lottery simply don't leave any traces in the fossil record. This makes it seem as if only purposeful mutations occur with a benevolent Intelligent Designer presiding over the process, but that simply ignores the fact that the vast majority of mutations that occur are defective and produce organisms that don't survive.
Mr. Braden supports his conclusions with the thinnest of evidence. He reveals the astounding fact that homo sapiens sapiens did NOT evolve from homo neanderthalensis! No kidding. Science has known this for decades. "Modern" humans and neanderthals emerged from Africa at separate times, encountered each other in Europe and western Asia and occasionally interbred. We know that with the exception of east Asians, most humans carry neanderthal genes. And guess what? Neanderthals had 46 chromosomes just like us. Mr. Braden presents a diagram of human and pre-human fossils connected by dotted lines which are labeled with question marks, indicating that we have no idea which fossil emerged from which. The fact is that there were a number of pre-human species coexisting in Africa and elsewhere, which probably interbred and produced offspring that left a confusing array of fossils. So what? Look at the dog species. Dogs, wolves, dogs, dingos, and coyotes are considered separate "species" but they can in fact interbreed with each other (although they rarely do). The "tree of life" is more like a bush than a tree, producing a bewildering array of species and sub-species that makes it difficult to connect all the dots. The fact of the matter is that the modern human species is extremely genetically homogeneous as species go, making it seem as if we're somehow "special." But this was not always the case. Chimpanzees have far more genetic diversity between neighboring populations than humans do across the entire globe. But this is a result of the fact that humans almost went extinct -- twice -- resulting in a severe genetic bottleneck tracing back to the time of "mitochondrial Eve," one woman in that tiny group of survivors who gave each of us all of our mitochondrial DNA.
I'm giving "Human by Design" five stars for readability and one star for scientific rigor, for an average of three stars.