The Evolution of the Human Brain: How Does It Account for the Knowledge Explosion?

The evolution of the human brain is a point of much debate among evolutionary biologists. Paleoneurology, which studies the evolution of the human brain, seems to be caught on the horns of a dilemma.

In evolutionary biology, there is the thought that the human brain attained it's current size roughly 200,000 years ago: "The evolution of a large, complex brain has been the defining feature of the human lineage - although human brain size has not changed over the past 200,000 years." (http://www.newscientist.com/article.ns?id=dn7974 ).

This poses a huge question: if the incredibly complex human brain has been around for that long, why has the great advancement of human knowledge only taken place within the last couple of thousand years, leading to the great knowledge explosion we have seen in recent history?

Human knowledge builds upon itself; why didn't the knowledge explosion take place 80,000 or 100,000 years ago, if the human brain has been roughly the same size during this time? Were human beings (homo sapien) out there "beating around the bush," hunting bugs and rodents, for all those thousands and thousands of years, even though they were walking around with an incredibly complex brain?

This apparent problem has indeed puzzled the great thinkers of our time. A recent approach has been to label the evolution of the human brain a "Special Event." The normal pace of evolution was somehow set aside, and the human brain evolved much more rapidly than normal. From a recent study:

"Genes that control the size and complexity of the brain have undergone much more rapid evolution in humans than in non-human primates or other mammals, according to a new study by Howard Hughes Medical Institute researchers."

"The accelerated evolution of these genes in the human lineage was apparently driven by strong selection. In the ancestors of humans, having bigger and more complex brains appears to have carried a particularly large advantage, much more so than for other mammals. These traits allowed individuals with "better brains" to leave behind more descendants. As a result, genetic mutations that produced bigger and more complex brains spread in the population very quickly. This led ultimately to a dramatic "speeding up" of evolution in genes controlling brain size and complexity."

"People in many fields, including evolutionary biology, anthropology and sociology, have long debated whether the evolution of the human brain was a special event," said senior author Bruce Lahn of the Howard Hughes Medical Institute at the University of Chicago. "I believe that our study settles this question by showing that it was."

Lahn and his colleagues reported their data in a research article published in the December 29, 2004, issue of the journal Cell ."

(taken from an article on the Howard Hughes Medical Institute website, http://www.hhmi.org/news/lahn3.html )

This presents a recurring problem for the Darwinian theory of evolution. Evolutionary theory is built upon the premise that evolution occurs gradually, over hundreds of thousands of years of time. Whenever data occurs that doesn't fit the theory, the theory of very gradual change through natural selection is set aside, and a new theory of rapid change is introduced. This is how the Darwinian theory of evolution "absorbs" evidence that contradicts the theory. However, once you allow various exceptions to the theory of evolution, you no longer have the foundation upon which the theory is built, and the theory needs to be set aside. Then the search for new scientific theories, better aligned to the facts, can begin.

The idea of "punctuated equilibrium" is another example of changing the theory of evolution to account for rapid change. Because there is a lack of evidence in the fossil record of very gradual change from one species to another, the idea of "punctuated equilibrium" has been introduced, which says that there have been sudden spurts and dramatic changes caused by mutations in various species. Again, gradual change is set aside, in favor of a theory of rapid change.

Concerning the evolution of the human brain, there is a contradictory school of thought in Paleoneurology, that the evolution of the human brain has actually slowed down over the past couple of million years:

ScienceDaily (Dec. 29, 2006) - "Despite the explosive growth in size and complexity of the human brain, the pace of evolutionary change among the thousands of genes expressed in brain tissue has actually slowed since the split, millions of years ago, between human and chimpanzee, an international research team reports in the December 26, 2006, issue of the journal, PLOS Biology."

"We found that genes expressed in the human brain have in fact slowed down in their evolution, contrary to some earlier reports," says study author Chung-I Wu, professor of ecology and evolution at the University of Chicago. "The more complex the brain, it seems, the more difficult it becomes for brain genes to change...."

The article goes on to report, "Genes that are expressed only in the brain evolved more slowly than those that are expressed in the brain as well as other tissues, and those genes evolved more slowly than genes expressed throughout the rest of the organism."

"The authors attribute the slowdown to mounting complexity of interactions within the brain. "We know that proteins with more interacting partners evolve more slowly," Wu said. "Mutations that disrupt existing interactions aren't tolerated."

This article also acknowledges the problem presented by the apparent "rapid evolution" of the human brain: "Humans have an exceptionally big brain relative to their body size. Although humans weigh about 20 percent more than chimpanzees, our closest relative, the human brain weighs 250 percent more. How such a massive morphological change occurred over a relatively short evolutionary time has long puzzled biologists."

(University of Chicago Medical Center (2006, December 29). Complexity Constrains Evolution Of Human Brain Genes. ScienceDaily. Retrieved January 15, 2008, from http://www.sciencedaily.com/releases/2006/12/061226095421.htm

Has the evolution of the human brain rapidly increased, or has it slowed down over the past couple of million years? Scientists differ radically in their conclusions.

There are other unanswered questions that can only be mentioned here: How can scientists "prove," in any scientific sense of the term, the pace of genetic evolution within the human brain, going back 50,000 or 100,000 years? Are there any repeatable scientific experiments which can conclusively "prove" how fast the human brain evolved 50,000 or 80,000 or 100,000 years ago? Or are we dealing with great amounts of speculation in this area?

The even more difficult dilemma for evolutionary theory is to explain why the explosion in human knowledge has only taken place within very recent history, using the evolutionary time scale.

Human knowledge accumulates over time - that knowledge builds upon itself and increases, to where we have the explosion in knowledge that is so evident today. How did it happen? Why did it happen so suddenly? Two or three thousand years, as compared to 200,000 years, is a very short amount of time. Yet it is claimed that the human brain has remained the same size for the past 200,000 years. (some scientists may speculate that it has been the same size for the past 150,000 years or 175,000 years, but the obvious point still remains).

Human knowledge is transmitted through language, and then through writing. This transmission of knowledge is a key in the accumulation and development of human knowledge. Some evolutionary researchers have estimated that human speech developed around 150,000 years ago:

"Phillip Lieberman has investigated the origin of speech for many years and has used this research to form hypotheses about the evolution of language. Lieberman suggests that speech improved greatly about 150,000 years ago when the larynx descended into the throat. According to the work of Lieberman and his colleagues, this descension improved the ability of early homonids to make key vowel sounds. Whereas the Neanderthals had a vocal tract similar in many respects to that of a new born baby, the elongated pharynx of a modern adult human is thought to enable production of a more perceptible repertoire of speech sounds. Lieberman suggests that though Neanderthals probably had some form of language, they may have failed to extend this language because they lacked the physical apparatus for producing a more sophisticated set of speech sounds."

(From "The Evolution of Language," at http://www.brainconnection.com/topics/?main=fa/evolution-language6 ).

This estimate that human speech began to develop 150,000 years ago makes the problem even more obvious: How could homo sapiens (man) have developed speech that long ago, having an incredibly complex computer called the human brain, and yet not have made great advances in language, writing, and the transmission of knowledge?

It is estimated, based on archological discoveries, that writing developed around 3,500 B.C. in Mesopotamia (see "Ancient Mesopotamia: The Invention of Writing" / Oriental Institute of the University of Chicago, at http://oi.uchicago.edu/OI/MUS/ED/TRC/MESO/writing.html).

This makes for a huge, huge gap between the development of speech, and the development of writing. For humans to have 144,000 plus years of speech, without developing writing, seems totally incredible. The human mind is much more clever than that. How could people be able to speak for that long, (or even half that long) without attempting to communicate through written symbols?

In fact, no matter which way these estimates and theories are developed, there are huge problems. The idea that man evolved very gradually, over hundreds of thousands of years of time, is full of problems and contradictions. If one takes the position that the human brain has slowed down in it's evolution since separating from the chimpanzee over a million years ago, then we have an incredible computer which is incredibly silent over hundreds and thousands of years of time.

If one takes the position that the evolution of the brain was a "Special Event" in which the normal pace of evolution was somehow miraculously sped up, then you have abandoned the Darwinian theory of very gradual evolution through natural selection, and you have introduced a new theory, of rapid change.

We need to think seriously about how long 150,000 years is, and how incredible the human brain is: with this great computer having the ability to reason, to think, to speak and communicate with other human beings, wouldn't knowledge have advanced much more rapidly? 150,000 years is a long, long, long time for man's knowledge to be flat-lined, until the gradually increasing curve of human knowledge in recent human history. This knowledge curve is now accelerating at a greater and greater rate.

The fact that the human brain does not fit in to the timescale of evolutionary theory is perhaps why scientists have felt compelled to theorize that the evolution of the human brain was a "Special Event," in which the evolutionary progress of the human brain was somehow dramatically increased. As quoted earlier, "Although humans weigh about 20 percent more than chimpanzees, our closest relative, the human brain weighs 250 percent more. How such a massive morphological change occurred over a relatively short evolutionary time has long puzzled biologists." http://www.sciencedaily.com/releases/2006/12/061226095421.htm

In "The Origin of the Species," Charles Darwin himself acknowledges that without a complete dependence on very slight, successive modifications to organisms through natural selection, his whole theory would break down: "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down." (Charles Darwin, The Origin of Species, p. 189).

Well, it has already been demonstrated, even by Darwinian evolutionists themselves, that rapid change must be introduced into evolutionary theory in various instances (two of which were cited above), to explain the facts. Thus, by his own admission, Darwin's theory has broken down.

Perhaps it's time to leave the sacred soil of evolution, and explore new options. Is it possible that the reason the knowledge explosion has only happened gradually within the last couple of thousand years, with greater and greater acceleration in recent time, is that human beings haven't been around that long, relatively speaking? A more recent appearance of man would explain the "massive morphological change that has long puzzled biologists," the great difference in brain size between humans and chimpanzees. A more recent appearance of man would also explain why the rapid advancement in knowledge has only occurred relatively recently. For man's incredible computer, the human brain, to be silent for hundreds of thousands of years is just not a viable option.

Is it possible that man is the product of some kind of creative intelligence, introduced onto planet earth? Rather than an automatic stonewalling by much of the academic community, why not allow for the possibility that there may be higher intelligence in the universe than ourselves? Perhaps thinking that we are the highest intelligence in the universe is the current day equivalent to thinking that the sun revolves around the earth. In other words, it is a paradigm that is outdated.

One could also make great advancements in the pursuit of honesty and truthfulness, and rather than engage in endless amounts of scientific speculation about what happened 100,000 or 500,000 or 1,000,000 years ago, we could simply admit that, scientifically speaking, we just don't know for certain what happened that long ago, in regard to man's origins. Some of the scientific community needs to recover the clear distinction between proven scientific facts (proven by repeatable scientific experimentation), and large amounts of speculation.

In light of the knowledge explosion, and our knowledge of the human brain, the theory that humankind evolved from lower primates gradually over hundreds of thousands of years of time is just not fitting in with the facts.

by M. A. Erickson

(Updated 4/20/08)

Evolution & The Human Brain

1. Inman, Mason, "Human Brains Enjoy Ongoing Evolution." NewScientist, 09 September 2005, http://www.newscientist.com/article.ns?id=dn7974

2. "Human Brain Evolution Was a 'Special Event'" Howard Hughes Medical Institute, December 29, 2005, http://www.hhmi.org/news/lahn3.html

3. "Complexity Constrains Evolution Of Human Brain Genes." Science Daily, Dec. 29,2006, http://www.sciencedaily.com/release/2006/12/061226095421.html

4. Peterson, Bret, "The Evolution of Human Language." P.6, Brain Connection, http://www.brainconnection.com/topics/?main=fa/evolution-language8

5. "Ancient Mesopotamia: The Invention of Writing." The Oriental Institute of the University of Chicago, http://oi.uchicago.edu/OI/MUS/ED/TRC/MESO/writing.html