A DIRECTION TO BIOLOGICAL EVOLUTION?

Evolution is a word that has a sense of advancement embedded in it. This is true both of its original meaning, and of its modern colloquial use. For most biologists, however, it is anathema to bracket evolution with progress; they chalk up in big letters on their blackboards: NEVER USE THE WORDS HIGHER AND LOWER. The phrase is Darwin's: he wrote it as a little memorandum to himself in the 1840s, but often ignored it in later life. He certainly thought of humans as being higher than all their animal relatives.

This book is concerned with what is surely the most conspicuous trend in life's history from the human point of view -- the progressive development of consciousness. Nevertheless, `mind', `consciousness', even `behaviour', have only recently started appearing in the indexes of evolutionary biology texts, and that taboo on `lower' and `higher' still obscures an understanding of the evolving mind.
Before we concentrate on advancing consciousness, can we discern any other directions in biological evolution? To establish whether any trends exist, we need to decide on what it is that is evolving. The obvious choice is the living organism. Then we can look at each of its characteristics, and judge whether there is any overall tendency of increase or decrease in the prevalence or importance of that feature over evolutionary time.
Broadly, there are two kinds of  trends observed in evolution: increases and improvements. In principle, at least, an increase in some characteristic of organisms should be objectively measurable -- it is a quantitative change -- while an improvement requires one to make a retrospective value-judgement, since it is a qualitative change. If one wishes to exclude all considerations of human values from evolution, then only quantitative trends could be considered.
For example, the prehistorian Gordon Childe measured evolutionary progress in terms of population increase. Using population size as the ordering principle for an evolutionary framework for existence yields an interesting hierarchy of forms, with rats, sparrows, and earthworms well ahead of people, insects doing better still (a million million or so by a 1960 estimate) and of course micro-organisms at the top. Alternatively, we could be a little more sophisticated, and acknowledge an overall evolutionary progress because the total number of living organisms has increased, together with their total bulk, their gross turnover of matter and energy, and their diversity of form.

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