Human genes only 30,000 to 50,000 species, not even more than wheat, corn, and the results of many species of whole-genome sequencing also showed that the gene number of different for constructing species and not too many contributions, so if the number of differentially expressed genes start looking for differences between humans and other species, the results must be wrong.
In 1921, a man named Xiao Fei rib Vince Painter American doctors, the number of mental patients in self-flagellation cut testicles when observed under a microscope found that only one set of genome sperm cells chromosome number 24 appears to .30 years later, people are using better equipment, clearly see the human genome only 23 pairs. At the time, it was a shock religious discovery, because at the time all apes suborder animals, the number of chromosomes is 24. And the legend before the ark of blood was open 24 pairs. 1980s, due to the development karyotype analysis techniques, and can be compared in detail primate chromosomes, chromosome found in almost all correspondence, only human chromosome 2 looks completely ape two medium-sized (Roche translocation) after chromosome end to end integration of new products! This genetic variation similar chromosome 64 and 66 chromosomes Marco Platts Mustang.
Why did you choose the chromosome 2? Molecular evolution has brought us a way to explain. Genes are selfish, conditions are selected gene is associated mode is easier to pass along. Branch evolution of human ancestors and chimpanzees occurred 500 million years ago in the Pleistocene. Some parts may retroviral infection ape ancestors after leaving future generations to let go "ape atlas", and these new "ape" look a little different: their feet are no longer with chimpanzees so bent, but more flat like, no longer suitable for four-legged run, more suitable its sagittal ridge is gone, the brain becomes larger, while the teeth bite force is reduced. At that time, their genes and not much difference with their ancestors, but the real one chromosome less: Although human genes have different numbers X0, XXY, even XXXY like, change from generations ago in which sick so two chromosomes together after can not be separated from this. Such chromosomal aberrations, since there is no cause defective gene function expression area, but their bodies abnormal hormone secretion, and even change the body's development model. They (not their) stand up straighter, and on land can run upright, and the amount of access to environmental information more and faster. All this stimulated the intelligence improved.
These are caused by changes in the number of chromosomes, which is the beginning of so-called reproductive isolation, the two different communities eventually become two different species. Like wild boar in the world there are 27 subspecies. Between subspecies and subspecies kernel type have some differences, chromosome number (2n) between 36 to 38, such as Western Europe 2n = 36 or 37 wild boar, wild boar Japan 2n = 38, the number of chromosomes are different from each other, but no breeding obstacle. Chromosome number of 56 bison and cattle after hybridization chromosome number 60 also have fertile offspring, but it is a different subspecies. Australopithecus and modern humans, differences in time, perhaps at the instant two chimpanzee chromosome fusion, that moment is called "chromosome 2," the emergence of a new chromosome, a new species, it will be born. It is human chromosome 2 stand out from apes key!
(Author: Chen Qingshan)
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