What Does it Mean to be Human?
Paul Coulter investigates what the physical, biological and social sciences have to say about Homo Sapiens.
Two Initial Observations
An initial observation of mankind will lead us to conclude that we stand apart from other species on earth for at least two reasons:
a) Our obsession with discovery and defining
We are the only species on earth that has named and classified other species. We have even invented a scientific label for ourselves – Homo sapiens, 'wise man' (a beautiful irony). This tendency to naming and classification lies at the root of science. We have a thirst to understand what things are composed of and how they work. We also have a need to capture the beauty of our world and explore dimensions of its meaning through art. We create things simply for the pleasure, expending large amounts of time and effort in the process, even if they have no functional value at all. Furthermore, we are the only species on earth that appears to ask deeper questions about meaning and purpose. The tendency, universal across human cultures, towards religion and philosophy has no observed parallel in other species.
b) Our ubiquity and ability to shape nature
Mankind is hugely successful at inhabiting the earth. We have found ways to live in every climate and ecosystem on every continent on earth, and even, for short periods, outside the atmosphere of our home planet. Furthermore, we are the only species that appears to have successfully domesticated animal species, even practising selective breeding among some species (notably dogs) that has led to a bewildering array of varieties. We have multiplied to such astounding numbers that many people are now afraid that our success will lead to our downfall – that human activity may threaten the earth's environment and cause a widespread extinction of life. Others, such as James Lovelock, the originator of Gaia Theory, argue that the earth functions as a self-regulating system that is capable of coping with the worst that mankind can throw at it. The earth was here before us, and will survive long after us, they claim. British philosopher John Gray (b.1948), who dubs humanity Homo rapiens because of our rape-like abuse of the earth's resources, predicts that human population will soon decline in the face of pressures from the environment. He quotes biologist Lynn Margulis, who writes: "No human culture, despite its inventiveness, can kill life on this planet, were it even to try". It seems that mankind's success illustrates the tension within us – we are capable of such inventiveness in using the earth's resources and surviving its challenges but also such destruction. Man does seem to have a unique potential for ubiquity and dominion over nature.
These observations are interesting, and we must ask what it is about our species that has made them possible. What is Homo sapiens, and is there anything unique about our species when compared to the other species that inhabit our planet? Different ideas have been suggested about what sets Homo sapiens apart from other animals. We will consider what three different branches of academic enquiry have to say on the matter – the physical sciences (chemistry and physics), the biological sciences (biology and genetics) and the social sciences (a broad category including disciplines such as law, anthropology and psychology).
The Physical Sciences
The physical sciences of physics and chemistry can compare our bodies to the stuff of the cosmos. At this level we discover that there is continuity. We are made up of the same elements and compounds that predominate in our universe. I belong in this cosmos and on this planet, and I am part of it. This may seem obvious to us today, but may not always have been obvious to the ancients.
The Biological Sciences
Biology can compare our bodies to those of other living creatures. We discover that there is significant continuity here too. Anatomy, physiology and biochemistry can all point to similarities. Notably the comparison is made with chimpanzees. Genetically, Homo sapiens is 96-99% similarity with Pan troglodytes (the common chimpanzee) depending on how the comparison is made. Between any two individual human beings the difference can be up to around 0.5%. However, this statistic is misleading, as even a visual comparison of a chimp with a human should suggest. In the first place, the organisation of genetic material in the two species is quite different (for example, there is an extra pair of chromosomes in chimps). Secondly, when the two species are compared at the protein level only around 20-30% of proteins are identical in amino acid sequence! Admittedly many of the proteins differ only in one or two amino acids, but it is notable that the headline statistic that is quoted is the figure for DNA sequence and not protein sequence. The difference between the two statistics is explained by a number of factors. Firstly it is clear that the differences between the DNA sequences are in places that make a great different to phenotype (the physical appearance of an organism). Added to this is the fact that protein function depends on more than simply DNA sequence – the same DNA sequence can give rise to numerous proteins as it can be spliced in alternative ways and other chaperone proteins are necessary in the cells to shape the protein chain into a functioning protein. Geneticist and popular science author Steve Jones (b.1944) has written:
A chimp may share 98 per cent of its DNA with ourselves but it is not 98 per cent human: it is not human at all – it is a chimp. And does the fact that we have genes in common with a mouse, or a banana say anything about human nature? Some claim that genes will tell us exactly what we really are. The idea is absurd.
Having highlighted the fact that man is not quite so closely akin to the chimpanzee as is sometimes implied, we must still acknowledge that there are great physical similarities. According to evolutionary psychologist Steven Pinker, the difference is primarily at the level of our brains:
The outsize brain of Homo sapiens is by any standard an extraordinary adaptation. It has allowed us to inhabit every ecosystem on earth, re-shape the planet, walk on the moon, and discover the secrets of the physical universe. Chimpanzees, for all their vaunted intelligence, are a threatened species clinging to a few patches of forest, and living as they did millions of years ago.
The advanced processing power of the human brain, according to Pinker, has elevated us above our closest relatives and explains our success. Still, chimps have brains that are not completely dissimilar from ours.
It is indisputable that human beings are remarkable in the complexity of their societies and the variety of their cultures and languages. Could these set us apart from other animal species? A BBC television documentary first broadcast in 2006 and hosted by Danny Wallace brought together research from a number of disciplines in addition to genetics to ask the question whether chimpanzees should have the same rights as human:
• Law – US lawyer Steven Wise suggested that based on the ability to reason, chimps should have the same rights as a three year old child at least.
• Sociology – chimps stay with their mothers for 12 years, unlike monkeys, making them socially more similar to humans than most other animal species.
• Culture – groups of chimps can learn and spread knowledge (e.g. within a group they may share one way to solve a particular problem). This may be seen as a rudimentary level of culture.
• Language – chimps make many sounds that communicate to others. Yet parrots show much more advanced language skills than chimps, even being able to learn some human words.
In addition, chimps show signs of emotion and social interaction that we more commonly associate with ourselves. Dutch primatologist, Frans de Waal (b.1941), writes:
I've argued that many of what philosophers call moral sentiments can be seen in other species. In chimpanzees and other animals, you see examples of sympathy, empathy, reciprocity, a willingness to follow social rules. Dogs are a good example of a species that have and obey social rules; that's why we like them so much, even though they're large carnivores.
As the BBC documentary showed, even language is not unique to human beings, although the extent of our language ability is certainly much greater than other species and we do have the unique skill of writing. In the words of John Gray:
The calls of birds and the traces left by wolves to mark off their territories are less forms of language than the songs of humans. What is distinctively human is not the capacity for language. It is the crystallization of language in writing.
Gray continues to suggest that the development of writing, and especially languages using an alphabet (rather than pictographs or ideographs), allowed the separation of ideas from reality that led, in his view, to the error in Western philosophy of distinguishing humans from other animals. Human language is remarkable, but what makes our language so complex? Is it a result of our “outsize brain”? And who is the 'me' who is writing these words and the 'you' that is reading them? Am I more than just a large brain on top of a strangely hairless and peculiarly upright body? We must turn now to the question of the human mind and consciousness.
 Lovelock’s seminal book, Gaia: a new look at life on earth, was first published by OUP in 1979.
 Lynn Margulis, quoted in Gray, John 2002, Straw Dogs: thoughts on humans and other animals, Granta, p.8.
 Wellcome Trust website: http://genome.wellcome.ac.uk/doc_wtd020730.html, accessed 23.10.10.
 Glazko G et al. 2005, 'Eighty percent of proteins are different between humans and chimpanzees', Gene 346:215-9 (14 Feb).
 Lennox, John 2007, God’s Undertaker: has science buried God?, Lion, pp.132ff., summarises these factors, drawing on the work of New York geneticist Barry Commoner.
 Steve Jones, quoted in Lennox, John 2007, God’s Undertaker: has science buried God?, Lion, p.131.
 Pinker, Steven 1997, How the Mind Works, Penguin, p.40.
 Elements from the October 2006 Horizon programme entitled 'Chimps are People Too' are archived online at http://www.bbc.co.uk/sn/tvradio/programmes/horizon/broadband/tx/chimps, accessed 25.10.10.
 Frans de Waal, quoted by Natalie Angier in a New York Times magazine article dated Jan 14th 2001, available: http://partners.nytimes.com/library/magazine/home/20010114mag-atheism.html, accessed 25.10.10.
 Gray, John 2002, Straw Dogs: thoughts on humans and other animals, Granta, p.56.
© 2010 Paul B Coulter
This article is reproduced here by the kind permission of the author.