American scientists drew a sketch of chimpanzee genome in 2003, but it was not accurate and complete enough. When comparing close relatives like chimpanzees and humans, it is difficult to say which genetic differences are real differences and which are just data errors. In the British journal Nature published on May 27th, 2004, a group of third-class chimpanzees from the old world announced that they had completed the sequencing of chromosome 22 of common chimpanzees. Scientists from Max Planck Institute, Japanese Institute of Physical and Chemical Research and China National South Center for Human Genome said that the data obtained by their joint sequencing were accurate enough to be used for reliable comparative analysis with the human genome.
Humans have 23 pairs of chromosomes, chimpanzees have 24 pairs-gorillas also have 24 pairs, but we are not chimpanzees. Chimpanzee chromosome 22 corresponds to human chromosome 2 1. The comparison shows that the difference between single bases (letters of genetic information) in the corresponding region of DNA sequence is 1.44%, that is, the difference of "single base substitution". This result was basically expected, which calmed some previous arguments. The error rate of this sequencing is less than one error per 10,000 "letters", so when comparing two chromosomes of chimpanzee and human, the difference caused by data error is less than 1% of all "letters" differences.
But the result of comparison is more accidental. Both human and chimpanzee genomes contain a lot of "junk DNA", which does not encode protein and has no effect on physiological functions. In the past, it was suspected that most of the genetic differences between humans and chimpanzees might exist in the junk area of the genome. In other words, among the genes that really work, the differences between them are even smaller. However, this study shows that the difference between useful parts of DNA sequence is not less than that between useless parts, at least on this chromosome. Scientists have examined 23 1 genes that are considered to be functional, and 83% of them are different, which affects the amino acid sequence of protein encoded by them (protein is a long chain of amino acid molecules), but small differences do not necessarily affect the function of protein; There are 47 genes with significant structural differences, accounting for about 20%. Chimpanzee genome has about 3 billion bases, and there are about 33 million bases on chromosome 22, accounting for about 1% of the total. From this perspective, if the genetic differences are evenly distributed on each chromosome, there may be thousands of significant differences between humans and chimpanzees. Finding the key genes that determine the difference between humans and chimpanzees will be more difficult than expected.
The comparison also shows that there are a lot of "intrinsic" differences between the two chromosomes. "Insertion" means that a piece of DNA appears in the DNA of one species, but not in the DNA of another species. "Deletion" refers to the loss of a piece of DNA in a species, and INDEL is a general term for these two differences. As many as 68,000 DNA fragments are different from chimpanzee chromosome 22 and human chromosome 2 1. Most of the clips are short, less than 30 letters, but some are as long as 54 thousand letters. Inder difference leads to 400,000 letters more on human chromosome 2 1 than chimpanzee chromosome 22, which means that the chromosomes of human and chimpanzee ancestors may be longer. In the process of their independent evolution, chimpanzee chromosomes lost more DNA fragments.
Peeping into the new discoveries brought by local areas makes scientists more eager to have an accurate and complete genome map of chimpanzees and compare it with the genomes of other close relatives such as humans and gorillas. The physiological and behavioral differences between humans and chimpanzees may not be the simple accumulation of small differences in gene number, but the comparison of gene differences is an indispensable cornerstone. For example, scientists in charge of this sequencing are planning to study two genes related to neural function, NCAM2 and GRIK 1. These two human genes contain some large DNA sequences that are not found in the chimpanzee version. This analysis will bring new clues to the study of human brain function. Previously, after studying a human family with genetic impairment of language ability, scientists found that a gene called FOXP2 is crucial to the use of language. It enables humans to flexibly control the muscles of the mouth and throat and make complex sounds. Protein encoded by this gene has two amino acid differences between humans and chimpanzees. Some scientists believe that this is why people's language ability far exceeds that of chimpanzees. The emergence and application of language is an important foundation for human beings to effectively transmit information, accumulate knowledge and create a civilized society. FOXP2 may not be the only language gene, and more related genes and their influence on the evolution of human brain have yet to be discovered.
The similarities and differences between humans and chimpanzees are only academic issues. Whether future research will bring ethical problems is unknown. If chimpanzees are classified as human beings (or people are classified as chimpanzees), should they be admitted that they have certain rights? Capturing, imprisonment, medical experiments and many other acts are terrible crimes for people, but for chimpanzees, at best, they will only violate the animal protection law under certain circumstances. If we look at chimpanzees more carefully, what changes need to be made? And this is not only something that human beings can do by making some material sacrifices, sometimes they have to face more difficult choices. For example, many medical research needs primates such as chimpanzees, some need to observe the efficacy and toxicity of new drugs in animals closest to humans, and some need to find the pathogenesis or related genes of certain diseases.
Chimpanzees are closest to humans in physiology, higher nervous activities and kinship, so they are the most ideal experimental animals for medical and psychological research and human space flight. However, international law clearly stipulates that scarabs cannot be used in medical research and other experiments for any reason or in any way.
Chimpanzees are higher animals most similar to humans. Studies have shown that some chimpanzees can not only master certain techniques and sign language after training, but also learn vocabulary with computer keyboards, and their ability even exceeds that of two-year-old children. However, researchers cannot train them to speak loudly in human language. Why? 1996 65438+1October19, American scientists found that chimpanzees also laugh when tickled, and they also breathe when laughing, which sounds like the sound of a chain saw, while humans temporarily stop breathing when talking or laughing, because people can control all parts of the diaphragm and muscles related to sound production well. Scientists believe that the key to speaking lies in the control of airflow by the nervous system. Humans can talk, but chimpanzees can't, which reveals the mystery that chimpanzees can't talk.
There is an amazing fact: chimpanzees even eat their close relatives-other primates, such as colobus monkeys and baboons. They even attack chimpanzees of the same kind and different groups for territory and food, similar to human wars. Jane goodall, a British female scientist, observed and studied whether apes can make tools. She studied the life of wild chimpanzees in Kenya under natural conditions. After a long period of patient work, she established a "friendship" with a group of wild chimpanzees, and then she often went to their places to observe.
She found that chimpanzees like eating termites very much. During the rainy season, the exit of the ant nest is sealed with thin soil, and termites wait in the cave for the rainy season to pass before leaving the nest. After seeing the seal of the ant nest, the chimpanzee tore off a layer of soil and carefully inserted a twig into the hole. At this time, termites are biting branches, and chimpanzees drag termites out and eat them. If there are leaves on the branches, chimpanzees will pick them off. If the branch is bent, chimpanzees will break the bent part, use the straight part of the branch, and so on until the branch is too short to use, and then discard it. The female scientist believes that all this seems to mean that chimpanzees have processed natural objects to suit their own purposes.
Chimpanzees don't always look for branches when they meet ant nests. They often break branches in advance and walk long distances on their backs, looking for termite nests and catching termites along the way.
Jane Goodall believes that chimpanzees' ability to catch termites is not innate instinct, but is obtained by observing and imitating their peers. 1. A study from June 5438 to February 2007 in Japan found that chimpanzees have better memories than humans.
The research team of Primate Research Institute of Kyoto University in Japan let digitally trained young chimpanzees compete with college students to instantly remember intuitive memories of things. As a result, chimpanzees are slightly better in accuracy and speed, and even college students who have been trained in intuitive memory for half a year are hard to win. Related research will be published in the American scientific journal Contemporary Biology on February 4, 2007.
Tetsuro Matsuzawa, a professor at Kyoto University who presided over this research, is well-known in the field of intelligence research of Japanese chimpanzees. He said that most people, including scientists, think that human beings have higher cognitive ability than chimpanzees, but the experimental results prove that this is not the case, and he himself was greatly surprised.
Matsuzawa let Ayum, a seven-year-old chimpanzee trained digitally, and two other five-year-old chimpanzees compete with college students in two stages. In the first stage, the computer will display one to nine numbers in different positions on the screen. When the subjects press the first number according to the size of the number, the other numbers will become white squares, and then they must press the other numbers in order according to the size of the number from memory. Therefore, chimpanzees are faster than humans.
In the second stage, the computer will instantly display five numbers, and then immediately turn them into white squares. When the digital display time is 0.7 seconds, the accuracy of Ayoum and college students is about 80%. However, when the number of seconds is shortened to 0.2 to 0.4 seconds, Ayoum can still maintain the accuracy rate of about 80%, while the accuracy rate of human beings drops to 40%.
It is said that a small number of human children have excellent intuitive memory like chimpanzees, which will be gradually lost with age, and young chimpanzees perform better than older chimpanzees. Matsuzawa pointed out: "This ability should come from being able to distinguish friends and enemies at a glance in nature or when fruits are ripe. In order to develop other abilities such as language, human beings may slowly lose this ability in the process of evolution. "
2. British research in February 2009: From birth to 9 months old, chimpanzee babies have better intelligence than humans.
Scientists have found that chimpanzees may be smarter than human babies of the same age, and human babies will not surpass chimpanzees until they are nine months old. Studies have shown that chimpanzee orphans who receive human "motherly care" perform better in cognitive ability tests than ordinary human children.
Professor Budd of the University of Portsmouth in the United Kingdom tested the cognitive ability of 46 young chimpanzees to understand their emotional responses to external things such as sounds and objects. The researchers also conducted the same test on human babies.
It was found that chimpanzees who were specially cared for by breeders had higher cognitive ability than human children of the same age raised by their parents, while human children did not surpass chimpanzees until they were nine months old.
The chimpanzees were kept in the orangutan nursery of yerkes National Primate Research Center in Atlanta, USA. Professor Budd found that these chimpanzees were smarter and happier than those who received general care. She explained: "The chimpanzees who are taken care of are not too nervous, don't need to hold comfort blankets often, have a good relationship with caregivers, and have less habitual movements such as shaking their bodies."
She said that research shows that chimpanzees, like humans, need emotional and physical support to grow into adult chimpanzees who are "completely adapted to the environment."
This is not the first time that a study has proved that chimpanzees have a high IQ. In the past, a study showed that chimpanzees can remember numbers better than some college students. They also know how to make food tools, and their hunting skills are very skilled. They can also learn the meaning of symbols, and their loved ones will feel sad when they die.
Short-term memory can surpass human beings.
A study shows that chimpanzees are smarter than humans, at least in terms of short-term memory. Related research was published at the annual meeting of the American Association for the Advancement of Science (AAAS).
Tetsuro Matsuzawa, a researcher at the Primate Research Association of Kyoto University, played a video showing that a chimpanzee named "Ayumu" has an unusual memory ability: when the numbers 1 to 9 disappear randomly on the screen, the chimpanzee can recall the exact order and position of each number. At the same time, Ayumu also learned the number 1- 19, and can touch them one by one in ascending order.