On May 23rd, Sweden will celebrate the birthday of Carl Linnaeus, the country's most famous scientist. As early as June+10, 5438, Sweden launched a series of themed activities to celebrate the 300th anniversary of Linnaeus' birth, and designated 2007 as the "Linnaeus Year" to commemorate the Swedish science veteran (Linnaeus was one of the founders of the Royal Swedish Academy of Science) and take this opportunity to inspire young people's love for science.
Karl Linnaeus was born at1May 23rd, 707 in a village in Smolan province in southern Sweden. As a priest, Linnai's father hoped that he would inherit his career, but time proved that his greatest legacy was his love for plants. Linnai's family has a small garden, and Linnai has developed the quality of a naturalist under the influence of his father since childhood.
Linnai is not a good student at school. But a teacher in Linnaeus discovered his talent in botany. The teacher persuaded Linnai's father to send Linnai to the nearest Lund University to study medicine. A year later, 1728, Linnai transferred to Uppsala University, the most famous university in Sweden.
Linnaeus never became a priest according to his father's earlier wishes. At Uppsala University, he studied medicine, but spent most of his time studying plants (this did not completely ignore his studies, because in Linnaeus's time, doctors used herbs to treat diseases, so botany at that time was also a part of medicine). At school, he also explored Lapland and central Sweden and studied the plants in those areas in detail.
1735, Linnaeus came to the Netherlands, where he obtained a medical degree. In the same year, he published a book "Systema Naturae", in which he put forward his own idea of classification, and divided nature into animal kingdom, plant kingdom and mineral kingdom. During that time, he also met many of the most famous scientists at that time. 1738, Linnaeus returned to Sweden and became a doctor. Three years later, he became a faculty member at Uppsala University. In addition to rebuilding the botanical garden of the university, he also trained many outstanding disciples. These disciples traveled around the world, and some even took part in Captain Cook's voyage around the world, sending back a large number of plant specimens for Linnaeus from all over the world.
In Linnaeus' time, many botanists named the same plant with different Latin names. As more and more specimens of animals and plants are transported from Asia, Africa and Latin America to Europe, botanists urgently need an effective naming system for animals and plants-it is not a good idea to describe a novel plant in one paragraph.
What is the meaning of the name? This flower, which we call a rose, will still smell the same if we change its name. In Shakespeare's plays, Juliet said this to Romeo. But for biologists, names are very important. Karl Linnaeus realized that in order to understand anything scientifically, everything needs a recognized common name. H.C.J.Godfray of the Department of Zoology, Oxford University, UK, commented in the journal Nature published on March 15 this year.
Linnai's solution is the so-called "double name method". Although Linnai was not the first person to use this naming method, he must have standardized it and made it widely accepted by biologists. According to the rules of Linnaeus, the name of a species consists of its generic name and a specific generic name. For example, Linnaeus named human beings Homosapiens (Latin, meaning wise man), while rice was OryzasativaL .. (The third word "L." here is the abbreviation of Linnaeus).
When the Natural System was first published in 1735, it was only a booklet with only 1 1 pages. When 10 was published in 1758, it was already a masterpiece, including tens of thousands of animals and plants named by Linnaeus' binomial method. Before that, 1753, he also published a book called "Species of Plants", which named more than 7,000 plants. These names have been used to this day.
Although Linnaeus initiated modern taxonomy and brought order to the biological world, he also made some mistakes. For example, Linnaeus applied the concept of race to human beings. He divided modern people into four subspecies: Americans, Asians, Africans and Europeans. Linnaeus described Americans as red-skinned, stubborn and irritable, Asians as yellow-skinned and greedy, Africans as dark-skinned and lazy, and Europeans as white-skinned aristocrats.
In the eyes of biologists today, this classification is undoubtedly a shallow mistake (but in some parts of the world, this classification seems to have some markets), because at the most fundamental level, human beings are a unified species. Linnaeus may not be a racist, but he was inevitably influenced by prejudice at that time.
Another mistake of Linnaeus is also related to his time. Linnaeus believes that God created all species, and these species will not change. In addition to binomial method, Linnaeus also established a hierarchical classification system: the top layer is "kingdom" (plant kingdom, animal kingdom and mineral kingdom), the bottom layer is "class", "order" and "genus", and finally "species". Although Linnaeus regards the wonder of nature as God's masterpiece, this classification system is actually a tree of life, implying that all living things have a common ancestor. Linnaeus did not accept this view (although he later admitted that species are changeable). This will have to wait until Charles Darwin appears.
1June 778, Linnaeus died in Uppsala. His son Carl Linnaeus Jr took over his father's teaching position in the university, but he also died five years later. Later, his mother and sisters sold Linnaeus' books, manuscripts and collections to Sir James edward smith, a British naturalist. He founded the linnean society of london, a society focusing on biological taxonomy, which still preserves most of Karl Linnaeus' collections.
1858, 1 In July, at the headquarters in linnean society of london, Charles Darwin and alfred wallace published their papers on the study of biological evolution (neither of them attended in person, but were read by John Burnett, secretary of the Society). The following year, Darwin published The Origin of Species. What Linnaeus ignored was what Darwin paid attention to: taxonomy not only allowed organisms to find their own position, but also revealed the evolutionary relationship among various organisms.
When Linnaeus named plants, it was based on the characteristics of plant reproductive organs, such as the number of stamens that determined which kind of plants belonged to. Taxonomy has also benefited from this biological revolution since scientists cracked the structure of DNA, the genetic material of life, in the mid-20th century. In the 1980s, scientists rearranged the taxonomic trees of tens of thousands of birds by comparing their DNA similarities.
Since 1990s, with the maturity of DNA sequencing technology, the genome sequences of more and more species have been determined. By comparing these data, scientists can solve some problems that were difficult to solve before. For example, scientists have now clearly realized that chimpanzees are the closest species to humans.
In 2003, PaulHebert, a biologist at the University of Guelph, proposed a method to distinguish different species with DNA. Although it is nothing new to determine the evolutionary relationship between organisms by using DNA, the genetic blueprint of organisms, Herbert's method is somewhat different. Herbert proposed to use a specific gene fragment to classify various organisms (just like using bar codes to distinguish different goods in supermarkets) without sequencing the whole genome.
This "bar code" gene is cytochrome c oxidase I(COI) gene from cell mitochondria. Mitochondria is the "power factory" of cells, and it has an independent set of DNA. The mutation rate of mitochondrial DNA is much higher than that of nuclear DNA, which constitutes a "molecular clock" for recording biological evolution. Herbert chose the 650-letter fragment of COI gene as the "barcode" of species classification-if two organisms belong to different species (that is, they shared a common ancestor before a certain period in history, but then embarked on different evolutionary paths), then the COI gene "barcodes" of the two organisms should be different.
DNA barcode is an attractive classification method. Traditional taxonomy relies on experts to identify biological forms, but if DNA barcodes are commercialized, even amateurs can identify species through small DNA barcode "scanning" equipment, for example, it can be used to quickly check whether the containers contain species whose import and export are prohibited by international conventions.
More importantly, DNA barcodes can also play a role in species protection and biodiversity research. In 2004, the research team led by Herbert studied the "barcode" of a butterfly in Costa Rica. After scanning the "bar codes" of nearly 500 butterflies, they found that this butterfly is actually composed of 10 species, which scientists had previously thought were the same species.
DNA barcode technology also has weaknesses. Scientists who support this technology admit that COI gene can't distinguish different kinds of plants well. There are also some animals that may not be correctly identified by a single DNA barcode. But if it can be improved, this technology will undoubtedly benefit taxonomists.
Linnaeus can't predict the revolution brought by DNA sequencing to taxonomy, and he probably can't predict how the information age will promote the development of taxonomy. Nowadays, many animal and plant taxonomy projects put their own databases on the Internet, so that scientists all over the world can easily obtain relevant taxonomic information. If Linnai were still alive, he would be thrilled with the news that at the beginning of this month, scientists announced a "life encyclopedia" project costing 654.38 billion US dollars. The plan will set up a free website (http://www.eol.org/) and put all the information of1.8000 kinds of animals and plants on the Internet. This may be an excellent commemoration of the 300th anniversary of Linnaeus's birth.