Some evolutionists agree that the appearance of humans could not be an accident:
With all these examples of convergence it is difficult to avoid the conclusion that the evolution of a humanoid creature was very much on the cards since at least the time of the Cambrian explosion more than half a billion years ago, when all the major groups of animals we see today originated. (Morris, 2002, p.26)
This convergence of the evolutionary process is unlikely to be a random product of adaptation and is more compatible with directed evolution. All the distinct characteristics of humans (brain, tongue, standing upright) do not make sense if the Neo-Darwinian view is taken. They only have long term benefits (thinking, language and freeing hands to enable tool making) that could not be anticipated by purely biological evolution. It is worthwhile to look at these features in more detail.
The claim that human consciousness was developed as an adaptive mechanism does not seem valid considering that most (if not all) of it, in fact, did not have an immediate advantage. The human brain has unique capacities that cannot be rivalled by any other organ; because of the brain, humans are the only species on the Earth that can calculate, philosophise, produce art, contemplate God or the structure of an atom. Yet, none of these abilities were of any use when the human brain appeared (the brain did develop further, but not much, throughout human history). The first humans, as all other animals, could do well for what they needed to survive with a smaller and less sophisticated brain. In fact, it was a big disadvantage. The bigger head (to accommodate the bigger brain) made birth more difficult, which must have increased the mortality rate of mothers and newborns alike. The soft part of the skull, to accommodate growth of the brain after birth, made infants more vulnerable to injury. Heaviness of the head could only make balance harder, and disproportional consumption of the oxygen and glucose by the brain contributed to the species being less rather than more physically fit. Also, a big brain is accompanied by a slow physical development that enables learning, but leads to the off-spring being dependent on their parents for longer, which is another adaptive disadvantage. So, if adaptation to the environment was the only decisive factor, species with the human brain should have disappeared as soon as they appeared.
A similar argument can be applied to the development of the human tongue, which is quite different from a chimpanzee tongue. It has a thick muscle at the back which enables humans to speak (chimpanzees have a flat tongue). However, a bulky tongue makes swallowing more difficult and therefore those who have it less adapted. True, language appeared later to be a huge advantage, but what use could early humans have of their potential to speak, when no language yet existed? The argument that the thickness gradually developed in parallel with the development of a primitive language does not hold water. It is extremely unlikely that the several sets of unrelated but right mutations affecting the brain, speech apparatus, and skeleton would have happened within the same species accidentally. For example, to have the control over breathing that is necessary for complex speech, humans needed a wider vertebral canal behind the ribcage than their predecessors such as Homo-erectus had; also the larynx descended in the throat and by being lower, contributed to this ability. Such synchronised events would require directed evolution.
Standing up must have been an adaptive disadvantage in the early stages too. It made humans slower, they could not climb trees well, and injuring one leg would be fatal. Yet, it was necessary for the development of consciousness because it enabled the anatomical change of the thumb and the use of hands for tool making.
In 1927, biologist Julian Huxley (who was the first Director-General of UNESCO and a founder of the World Wildlife Fund) wrote:
Biology... has thus revealed man's place in nature. He is the highest form of life produced by the evolutionary process on this planet, the latest dominant type, and the only organism capable of further major advance or progress. Whether he knows it or not, whether he wishes it or not, he is now the main agency for the further evolution of the earth and its inhabitants. In other words, his destiny is to realise new possibilities for the whole terrestrial sector of the cosmic process, to be the instrument of further evolutionary progress on this planet. (in Edmunds, 1997, p.172)
A view like this may be unpopular nowadays for the fear of human hubris, but if the main point that it contains is not recognised, there is a real danger that the unique responsibility that humankind has will go unacknowledged too. This point is that evolution continues through the individual and group development of human beings. As biological species, individuals and societies can also regress, stagnate, as well as progress. However, due to the complexity of the brain and its unprecedented dynamic, humans have a potential to substantially develop even within a single life. This potential for personal development makes the process incomparably faster than biological evolution, and also allows huge variety even within the same species. The next chapter will address this subject.
- . On the darker side, he is also associated with eugenics, although he quickly became its fervent critic, advocating that race is a cultural not a biological term.