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The terminology did not settle down until some time after the publication of the Origin of Species. The word evolved in a modern sense was first used in 1826 in an anonymous paper published in Robert Jameson's journal and evolution was a relative late-comer which can be seen in Herbert Spencer's Social Statics of 1851, [a] and at least one ...
The development of molecular genetics has revealed the record of evolution left in organisms' genomes: dating when species diverged through the molecular clock produced by mutations. [283] For example, these DNA sequence comparisons have revealed that humans and chimpanzees share 98% of their genomes and analysing the few areas where they ...
Due to the damaging effects that mutations can have on cells, organisms have evolved mechanisms such as DNA repair to remove mutations. [5] Therefore, the optimal mutation rate for a species is a trade-off between costs of a high mutation rate, such as deleterious mutations, and the metabolic costs of maintaining systems to reduce the mutation ...
Biologists assumed that an organism was a straightforward reflection of its component genes: the genes coded for proteins, which built the organism's body. Biochemical pathways (and, they supposed, new species) evolved through mutations in these genes. It was a simple, clear and nearly comprehensive picture: but it did not explain embryology.
In biology, evolution is the process of change in all forms of life over generations, and evolutionary biology is the study of how evolution occurs. Biological populations evolve through genetic changes that correspond to changes in the organisms' observable traits.
The European mutation, called the LP allele, is traced to modern-day Hungary, 7,500 years ago. In the twenty-first century, about 35% of the human population is capable of digesting lactose after the age of seven or eight. [15] Before this mutation, dairy farming was already widespread in Europe. [74]
[29] [30] This held that species went through periods of rapid mutation, possibly as a result of environmental stress, that could produce multiple mutations, and in some cases completely new species, in a single generation, based on de Vries's experiments with the evening primrose, Oenothera, from 1886.
Some nonlethal regulatory mutations occur in HOX genes in humans, which can result in a cervical rib [95] or polydactyly, an increase in the number of fingers or toes. [96] When such mutations result in a higher fitness, natural selection favours these phenotypes and the novel trait spreads in the population.