COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.Natural selection, then, provides a more compelling mechanism for adaptation and evolution than Lamarck's theories. However, it was Darwin’s concept of natural selection, wherein favorable traits like a long neck in giraffes suvived not because of aquired skills, but because only giraffes that had long enough necks to feed themselves survived long enough to reproduce. Lamarck theorized that behaviors aquired in a giraffe's lifetime would affect its offspring. In Lamarck’s thinking, the offspring of a giraffe that stretched its neck would then inherit a slightly longer neck. The example he gave stated the ancestors of giraffes might have adapted to a shortage of food from short trees by stretching their necks to reach higher branches. Another French thinker, Jean Baptiste Lamarck, proposed that animals could adapt, pass on their adaptations to their offspring, and therefore evolve. He was a French mathematician who believed that organisms changed over time by adapting to the environments of their geographical locations. Scientists who studied adaptation prior to the development of evolutionary theory included Georges Louis Leclerc Comte de Buffon. One example of behavioral adaptation is how emperor penguins in Antarctica crowd together to share their warmth in the middle of winter. Organisms can also exhibit behavioral adaptation. Tibetans seemed to have evolved genetic mutations that allow them to use oxygen far more efficently without the need for extra hemoglobin. However, continuously high levels of hemoglobin are dangerous, so increased hemoglobin levels are not a good solution to high-altitude survival in the long term. Most people can survive at high altitudes for a short time because their bodies raise their levels of hemoglobin, a protein that transports oxygen in the blood. Breathing air that thin would cause most people to get sick, but Tibetans’ bodies have evolved changes in their body chemistry. Tibetans thrive at altitudes where oxygen levels are up to 40 percent lower than at sea level. An example of biological adaptation can be seen in the bodies of people living at high altitudes, such as Tibet. They can adapt biologically, meaning they alter body functions. Organisms can adapt to an environment in different ways. This enables better survival and reproduction compared with other members of the species, leading to evolution. The idea of natural selection is that traits that can be passed down allow organisms to adapt to the environment better than other organisms of the same species. In developing the theory of evolution by natural selection, Wallace and Darwin both went beyond simple adaptation by explaining how organisms adapt and evolve. Wallace believed that the evolution of organisms was connected in some way with adaptation of organisms to changing environmental conditions. Although scientists discussed adaptation prior to the 1800s, it was not until then that Charles Darwin and Alfred Russel Wallace developed the theory of natural selection. In evolutionary theory, adaptation is the biological mechanism by which organisms adjust to new environments or to changes in their current environment.
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