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Those parts of the biosphere which are characterised by physical extremes are generally populated by sparse numbers of individuals and species.

Conversely, where biosphere resources are abundant then species diversity and total numbers of individuals increase rapidly.

This feature can be best illustrated by counting the number of species of beetles, or of reptiles that occur in distinct latitudinal lands, see Table. The varying capability of habitats to support a population is termed the ‘habitat productivity’ or ‘species diversity.’

Organisms have evolved so that they can complete their life cycles under the most extreme habitat conditions. The evolution may involve physical body change, for example the sole (so/ea solea), a shallow in­shore salt water fish which has become flattened with a consequent movement of the life eye position until it comes to be close to the right eye (which remains in its original position).

A restructuring of the jaws and a change in fin and muscle positions compared with their free swimming cousins completes the physical changes of the sole. Physical change is usually accompanied by behavioural change which eventually leads to physical change.

Of all the species in the biosphere none is so adept at survival as mankind. What is easily overlooked is that whereas today, and for the past several hundreds of years, man deliberately strives to enhance his chances of survival, the original situation was very different.

Our original hominoid ancestors showed no deliberate tendency to outperform the other plants and animals. Whatever happened all those millennia ago did so in an entirely voluntary manner.

The Uniqueness of Man

The fundamental change which occurred in group of ancient primates was the emergence of a behavioural trait which persisted for a sufficient time such that a physical (skeletal) change occurred.

The specific behavioural change was one in which instead of moving on all four limbs, proto-man gradually made less use of his fore-limbs for movement. A bipedal gait initially had many disadvantages compared to four-legged movement. It was slower, more clumsy and was a less well balanced form of movement. Its advantage was that it released the fore limbs for other functions.

Taken on its own, bi-pedal gait does not bestow any advantage- indeed the opposite. In order for the new form of locomotion to be useful a whole host of ancillary behavioural patterns become necessary and, of greater significance, some substantial neuro-physical changes must also take place.

These have been summarised in Table. As with so many other lines of evolution, once a successful strategy has been devised then so it becomes difficult for that sequence to be altered.

What started as a chance behavioural pattern has today established mankind as the dominant organism on this planet. Such is our technological and scientific power it is difficult to imagine how, if ever, man will be replaced as the dominant organism.

The behavioural and physical adaptations which have allowed us to achieve dominance over all other plants and animals have been accompanied by a single mindedness and ruthlessness in the ways in which we relate to other organisms. Many other animals (and some plants) show a similar determination to survive. These species are usually the ecosystem dominants, for example, the lion of the African savanna.

The main difference between the way in which ecosystem dominance has been achieved by man and that of other animals is that the latter achieve their dominance by working within the ecosystem boundaries. Man, because of his deliberate attempts to achieve dominance, has removed himself from the confine of the ecosystem.

But man is still bound by animalistic requirements and is dependent upon the biosphere to provide the raw materials necessary for survival. It is the overlooking of this fact which has led man to over-exploit the biosphere and its components and which has given rise to resources depletion. It is for this very reason that conservation of the biosphere, its resources, ecosystems and species has become necessary.

It might be argued that Homo sapiens as a species has achieved dominant status specifically because of our-non-compassionate attitudes to other species.

A conservationist attitude has not been a traditional part of the human characteristic. If such an attitude were to be rigidly applied both now and in the future, then it might be sufficient to threaten man’s position as the dominant species on this planet.