Mystery of Homo Sapiens (continued)
By Alan F. Alford
The Mystery of
the Human Brain
The greatest mystery of Homo sapiens is its incredible brain. During
the last fifteen years, scientists have used new imaging technologies
(such as positron-emission tomography) to discover more about the
human brain than ever before. The full extent of the complexity of
its billions of cells has thus become more and more apparent. In
addition to the brain's physical complexity, its performance knows
no bounds - mathematics and art, abstract thought and conceptualisation
and, above all, moral conscience and self-awareness.
of the human brain's secrets remain shrouded in mystery, enough
has been revealed for National Geographic to have boldly
described it as 'the most complex object in the known universe'.
see the brain as nothing more than a set of algorithms, but they
are forced to admit that it is so complex and unique that there
is no chance of reverse engineering the evolutionary process
that created it. The eminent scientist Roger Penrose, for example,
I am a
strong believer in the power of natural selection. But I do
not see how natural selection, in itself, can evolve algorithms
which could have the kind of conscious judgements of the validity
of other algorithms that we seem to have.
the fossil record tell us about our evolving brain capabilities?
The data varies considerably and must be treated with care (since
the sample sizes are limited), but the following is a rough guide.
hominid Afarensis had around 500cc and Habilis/Australopithecus had
around 700cc. Whilst it is by no means certain that one evolved
from the other, it is possible to see in these figures the evolutionary
effects over two million years of the hominid's new environment.
As we move
forward in time to 1.5 million years ago, we find a sudden leap
in the cranial capacity of Homo erectus to around 900-1000cc.
If we assume, as most anthropologists do, that this was accompanied
by an increase in intelligence, it represents a most unlikely
macromutation. Alternatively, we might explain this anomaly by
viewing erectus as a separate species whose ancestors
have not yet been found due to the poor fossil records.
after surviving 1.2 to 1.3 million years without any apparent
change, and having successfully spread out of Africa to China,
Australasia and Europe, something extraordinary happened to the Homo
erectus hominid. Perhaps due to climatic changes, his population
began to dwindle until he eventually died out. And yet, while
most Homo erectus were dying, one managed to suddenly
transform itself into Homo sapiens , with a vast increase
in cranial capacity from 950cc to 1450cc.
thus appears like an hourglass, with a narrowing population of Homo
erectus leading to possibly one single mutant, whose improved
genes emerged into a new era of unprecedented progress. The transformation
from failure to success is startling. It is widely accepted that
we are the descendants of Homo erectus (who else was there
to descend from?) but the sudden changeover defies all known
laws of evolution. Hence Stephen Jay Gould's comment about the
'awesome improbability of human evolution'.
Why has Homo
sapiens developed intelligence and self-awareness whilst
his ape cousins have spent the last 6 million years in evolutionary
stagnation? Why has no other creature in the animal kingdom
developed an advanced level of intelligence?
answer is that we stood up, thereby releasing our two arms, and
began to use tools. This breakthrough accelerated our learning
through a 'feedback' system, which stimulated mental development.
scientific research does confirm that electrochemical processes
in the brain can sometimes stimulate the growth of dendrites
- the tiny signal receptors which attach to the neurons (nerve
cells). Experiments with caged rats have shown greater brain
mass developing where the cages are full of toys rather than
But is this
answer too simple? The kangaroo, for instance, is extremely dexterous
and could have used tools but never did, whilst the animal kingdom
is full of species which do use tools but have never become intelligent.
Here are some examples. The Egyptian vulture throws stones at
ostrich eggs to crack their tough shells. The woodpecker finch
in the Galapagos Islands uses twigs or cactus spines in up to
five different ways to root out wood-boring insects from rotten
trees. The sea otter on the Pacific coast of North America uses
a stone as a hammer to dislodge its favourite food, the abalone
shellfish, and uses another stone as an anvil to smash open the
examples of simple tool use, but there is no sign of it leading
anywhere. Our nearest relatives, the chimpanzees, also make and
use simple tools, but can we really see them evolving intelligence
at our level? Why did we acquire a brain which qualifies as 'the
most complex object in the known universe', whilst the chimpanzees
In order to throw down the gauntlet to the evolutionists, it is essential
to conduct the fight in their own territory. A basic understanding
of state-of-the-art Darwinian thinking is therefore essential.
first put forward his theory of evolution by natural selection,
he could not possibly have known the mechanism by which it occurred.
It was almost one hundred years later, in 1953, that James Watson
and Francis Crick discovered that mechanism to be DNA and genetic
inheritance. Watson and Crick were the scientists who discovered
the double helix structure of the DNA molecule - the chemical
which encodes genetic information. Our schoolchildren now understand
that every cell in the body contains 23 pairs of chromosomes,
onto which are fixed approximately 100,000 genes making up what
is known as the human genome. The information contained in these
genes is sometimes switched on, to be read, sometimes not, depending
on the cell and the tissue (muscle, bone or whatever) which is
required to be produced. We also now understand the rules of
genetic inheritance, the basic principle of which is that half
of the mother's and half of the father's genes are recombined.
genetics help us to understand Darwinism? It is now understood
that our genes undergo random mutations as they are passed through
the generations. Some of these mutations will be bad, some good.
Any mutation which gives a survival advantage to the species
will by and large, over many many generations, spread through
the whole population. This accords with the Darwinian idea of
natural selection - a continuous struggle for existence in which
those organisms best fitted to their environment are the most
likely to survive. By surviving, an organism's genes are more
likely, statistically, to be carried into later generations through
the process of sexual reproduction.
misconception with natural selection is that genes will directly
improve in response to their environment, causing optimal adjustments
of the organism. It is now accepted that such adaptations are
in fact random mutations which happened to suit the environment
and thus survived. In the words of Steve Jones: 'we are
the products of evolution, a set of successful mistakes'.
is the process of evolution? The experts all agree with Darwin's
basic idea that natural selection is a very slow, continuous
process. As one of today's great champions of evolution, Richard
Dawkins, has put it: 'nobody thinks that evolution has ever been
jumpy enough to invent a whole new fundamental body plan in one
the experts think that a big evolutionary jump, known as a macromutation,
is extremely unlikely to succeed, since it would probably be
harmful to the survival of a species which is already well adapted
to its environment.
thus left with a process of random genetic drift and the cumulative
effects of genetic mutations. But even these minor mutations
are thought to be generally harmful. Daniel Dennett neatly illustrates
the point by drawing an analogy with a game whereby one tries
to improve a classic piece of literature by making a single typographical
change. Whilst most changes such as omitted commas or mis-spelled
words would have negligible effect, those changes which were
visible would in nearly all cases damage the original text. It
is rare, though not impossible, for random change to improve
are already stacked against genetic improvement but we must add
one further factor. A favourable mutation will only take hold
if it occurs in small isolated populations. This was the case
on the Galapagos Islands, where Charles Darwin carried out much
of his research. Elsewhere, favourable mutations will be lost
and diluted within a larger population and scientists admit that
the process will be a lot slower.
If the evolution
of a species is a time-consuming process, then the separation
of one species into two different species must be seen as an
even longer process. Richard Dawkins compares the genes of different
species to rivers of genes which flow through time for millions
of years. The source of all these rivers is the genetic code
which is identical in all animals, plants and bacteria that have
ever been studied. The body of the organism soon dies but, through
sexual reproduction, acts as a mechanism which the genes can
use to travel through time. Those genes which work well with
their fellow-genes, and which best assist the survival of the
bodies through which they pass, will prevail over many generations.
causes the river, or species, to divide into two branches? To
quote Richard Dawkins:
are controversial, but nobody doubts that the most important
ingredient is accidental geographical separation.
as it may seem, statistically, for a new species to occur, the
fact is that there are today approximately 30 million separate
species on Earth and it is estimated that a further 3 billion
species may have previously existed and died out. One can only
believe this in the context of a cataclysmic history of planet
Earth - a view which is becoming increasingly common. Today,
however, it is impossible to pinpoint a single example of a species
which has recently (within the last half a million years) improved
by mutation or divided into two species.
exception of viruses evolution appears to be an incredibly slow
process. Daniel Dennett recently suggested that a time scale
of 100,000 years for the emergence of a new animal species would
be regarded as 'sudden'. At the other extreme, the humble horseshoe
crab has remained virtually unchanged for 200 million years.
The consensus is that the normal rate of evolution is somewhere
in the middle. The famous biologist Thomas Huxley, for example,
changes [in species] occur over tens of millions of years,
while really major ones [macro changes] take a hundred million
years or so.
In the absence
of fossil evidence, we are dealing with extremely theoretical
matters. Nevertheless, modern science has managed, in a number
of cases, to provide feasible explanations of how a step-by-step
evolutionary process can produce what appears to be a perfect
organ or organism. The most celebrated case is a computer-simulated
evolution of the eye by Nilsson and Pelger. Starting with a simple
photocell, which was allowed to undergo random mutations, Nilsson
and Pelger's computer generated a feasible development to full
camera eye, whereby a smooth gradient of change occurred with
an improvement at each intermediate step.
of gradiented, or incremental, change is central to the modern
view of evolution. The key point is that for a mutation to successfully
spread through a population, each step will only be as perfect
as it needs to be to give a survival edge. Richard Dawkins uses
the example of cheetahs and antelopes to demonstrate how this
genetic rivalry works; the cheetah seems perfectly designed to
maximise deaths among antelopes, whilst the antelope seems equally
well-designed to avoid death by cheetah. The result is two species
in equilibrium, where the weakest individuals die but both species
survive. This principle was first put forward by Alfred Wallace
when he stated that: 'nature never over-endows a species beyond
the needs of everyday existence'. It is the same situation as
the trees in a dense forest, which have over a very long time
maximised their height in competition for the light.
A Brain Teaser
The human brain at birth is approximately one quarter of its adult
size. The need for a large skull to house the fully grown adult brain
causes human babies to have extremely large heads at birth (relative
to other primates). Passing the baby's head through the birth canal
is therefore the major problem of childbirth and causes acute pain
to the mother.
biologists, gynaecologists and anatomists, it is a mystery why
the female did not evolve a larger birth canal. The answer is
simple - engineering. Such a change would have required a radical
redesign in bone structure - an impossibility within the limits
of a body which is designed for bipedal walking. The birth canal
is thus the limiting factor to man's cranial capacity.
If we cast
our minds back several hundred thousand years, before hospitals
and midwives existed, it is not difficult to imagine that a large
number of infants were stillborn or their mothers killed in childbirth.
It therefore seems extremely doubtful that natural selection
would have favoured a gene for large brain size, with its potential
harmful consequences to both mother and child. Simply put, such
a gene would not have successfully spread.
much more likely that natural selection would have deselected
the large brain and would have stumbled instead upon a better
neural networking system or, alternatively, a means to switch
skull growth from pre-birth to post-birth. The fact that it did
not, and the fact that the wiring of the brain also seems highly
efficient in design, strongly indicates two essential evolutionary
requirements. First an incredibly long period and secondly a
pressing need to develop its optimum potential.
point is particularly crucial for it implies that the evolving
hominid had a pressing need to develop a brain with advanced
capabilities in such things as art, music and complex mathematics.
however, agree that natural selection should only bestow as much
of a new and better physical trend as is needed for survival.
The cheetah and antelope which I mentioned earlier are typical
of Richard Dawkins' world, where progress comes from a constructive
tension between species - a critical balance between survival
and extinction. According to this scenario, the genes which make
good brains are favoured by natural selection only because they
are absolutely critical to the survival of the species.
Dawkins illustrates this point with a story of how the motor
car magnate Henry Ford instructed his staff to survey the scrapyards
and find out which components of the 'Model T' did not wear out.
As a result, the kingpins were re-engineered to a lower standard.
According to Dawkins, the same principle applies to evolution
by natural selection. It is worth quoting Dawkins in full, for
we will turn this argument back against him:
possible for a component of an animal to be too good, and we
should expect natural selection to favor a lessening of quality
up to, but not beyond, a point of balance with the qualities
of the other components of the body.
of this principle can be judged from the fact that the operation
of the brain requires no less than 20 per cent of our body energy.
Its complexity thus makes it an expensive organ to run.
is the evolutionary crunch. As efficient as the brain is, the
average human being does not use it to anywhere near its full
capacity. How then can Dawkins explain the massive over-engineering
of the human brain? What useful survival skills did music and
mathematical ability give to our hunter ancestors? Why has the
over-engineered brain not been de-selected?
would no doubt argue that the algorithms of the brain did not
evolve for music and mathematics, but were 'exapted' from
developments for other purposes. No-one, however, can suggest
what these other purposes might have been, that would have led
to such a highly evolved mental capability. Charles Darwin's
partner, Alfred Wallace, clearly recognised the contradiction
when he wrote:
Wallace aired his suspicion that another factor - 'some unknown
spiritual element' - was needed to account for man's unusual
artistic and scientific abilities.
If we go
back one million years to a time when man was fighting for survival,
how can Richard Dawkins explain how evolution seems to have favoured
non-essential abilities in art, music and mathematics? Why did
the brain, which must have been at least partly evolved already,
not benefit from any types of useful survival skills such as
enhanced smell, infra-red vision, improved hearing and so on?
nail in the evolutionists' coffin is this: where was the competitor
that caused the brain of Homo sapiens to evolve to such
an extreme level of size and complexity? What rival caused intellectual
ability to be such an essential survival development for our
species? Who were we trying to outsmart?
competition be the explanation? In modern times our most significant
achievements - space travel and nuclear weapons for example -
have come from superpower competition. Did primitive men split
into competitive, rival groups? Could Neandertal have been a
competitive threat to his fellow Homo sapiens? On the
contrary, the evidence suggests that Neandertal and Cro-Magnon
co-existed peacefully. Furthermore, early hominids continued
to use simple stone tools for millions of years up to about 200,000
years ago; there is no sign of any escalation in tool use caused
by an inter-species conflict.
So, in the
absence of an intellectual rival that fits the time frame, the
orthodox evolutionary scenario for the human brain seems to be