Scientists are fond of running the evolutionary clock backward, using DNA analysis and the fossil record to figure out when our ancestors stood erect and split off from the rest of the primate evolutionary tree.But the clock is running forward as well. So where are humans headed?
The earth has been capable of supporting life for about 3 billion years, and is expected to continue being able to support life for about 5 billion years in the future. Thus if we view the period of being able to support life as 24 hours, then we are now about 9 o'clock in the morning, humans diverged from the apes about a minute ago and the human species started to exist 1-2 seconds ago.
The average life span of a species on earth is a few million years. Every year, thousands of species cease to exist and thousands of new species are created. Will thus the human species cease to exist in a few million years, like most other animals? If so, why, and what will replace it? Or are humans so unique and different from other species, that experience from other species cannot be applied, and humans may continue to exist for a much longer time?
Humans differ so much from other species, that human future development may not be governed by the same principles as other animals. [Miller 2004] says that humans and human society should be seen as a fourth system of structured energy, Tetrology, different from the previous atomic, chemical and biological systems.
Miller says that humans differ in the use of advanced technology, use of controlled energy, use of clothes, use of sense-enhancements like glasses, telescopes or microscopes, advanced social organization, advanced language.
On the other hand, it is apparent that many typical animal behaviors also occur in humans, as has been pointed out by [Morris 1967-1997] and [Diamond 1993]. Humans have a mating behavior and an aggressive behavior which is obviously inherited from our animal ancestors.
This is important when discussing the future of the human species, because humans may be so different that experience from animals cannot tell us anything about the future of Homo Sapiens
Homo Sapiens can evolve through natural selection or through breeding or genetic manipulation. Breeding and genetic manipulation is most probable for a few people in technically evolved countries.
Natural selection is most effective when many animals die before reproduction. Thus, natural selection is more effective in developing countries. In industrial countries, medical development allows most of those who would die to live and reproduce.
Speciation forms the bridge between the evolution of the populations and the evolution of the taxonomic diversity .the diversity of organisms is the consequence of CLADOGENESIS , the branching or multiplication of the lineages , each of which then evolves(by ANAGENESIS, or evolution within species) along its own path. Each branching point in the great phylogenetic tree of the life marks a speciation event: the origin of two species from one. Many events in history of evolution are revealed to us only by virtue of speciation. If a single lineage evolves great changes but does not branch, the record of all steps toward its present form is erased , unless they can be found in fossil record. But if the lineage branches frequently, and if intermediate stages of a character are retained in some branches that survive to the present , then the history of the evolution of the feature may be represented , at least in part , among living species. The human species (Homo Sapiens sapiens) started its existence between 110 000 and 50 000 years ago. Its development diverged from the apes about 5 million years ago. In traditional classifications primate super family Hominoidea consists of three families: the gibbons (Hylobatidae), the human family (Hominidae), and the great apes (Pongidae). DNA sequence differences imply that the chimpanzees and human lineages diverged 5 to 6 million years ago. No chimpanzee fossils have been found, but hominin fossil are known from as far back as the late Miocence(The term “hominin” has been applied to the hominind that are the sister group of the chimpanzees).the hominin fossil record provides unequivocal evidence of general , more or less unidirectional trends in many characters, such as cranial capacity , a measure of brain size. It shows beyond any doubt that modern humans evolved through many intermediate steps from ancestors that in most anatomical respects were apelike throughout hominin evolution different hominin features evolved at different rates (“mosaic”evolution). On an average the brain sizes (cranial capacity) increased throughout hominin history, although not at a constant rate, and there were progressive changes from afarensis to africanus to erectus to sapiens, in many other features such as teeth, face, pelvis, hands, and feet.
Will Homo Sapiens Deteriorate
Some people say that the lack of effective natural selection for humans in industrial countries will cause the human species to deteriorate, since natural selection is needed to keep a species healthy. As a simple example, the existence of spectacles would cause more people to be born near sighted.
However, this is counteracted by immigration of people from less developed countries. This immigration is today so large, that it can probably counter the risk of deterioration of the species as a whole.
Also, future use of genetic manipulation and intentional breeding can be expected to counteract degradation.
Evolutionary development is sometimes thought of as exhibiting an inexorable trend towards higher, more complex, and normatively worthwhile forms of life. Can we trust evolutionary development to take our species in broadly desirable directions? Starting from primitive, unconscious life, biological evolution has led to the development of ever more advanced organisms, including creatures that have minds, consciousness, language, and reason. More recently, cultural and technological development, which exhibit some parallels with biological evolution, have enabled our species to progress at a vastly accelerated pace. The past few hundred years have seen enormous improvements in human life-span, labor productivity, scientific knowledge, and social and political organization, which have enabled billions of people to enjoy unprecedented opportunities for enjoyment and personal development. On a historical as well as on a geological timescale, the big picture shows an overarching trend towards increasing levels of complexity, knowledge, consciousness, and coordinated goal-directed organization, a trend which, not to put too fine a point on it, we may label “progress”.
