Belyev selection of foxes for tameness, which ended up behaving and looking like domestic dogs (black-white colors, ears down, tails up, six-month heat for females, sounds) Artificial selection: humans chose species for breeding based on some criteria. One could say that the male aremanipulating the females by singing to them. The sounds of canaries male caues the femalse ovaries to swell and secrete hormones that bring them into reproductive condition. Galapagos Islands on the other hand comes from a spanish name for turtoise. There is an inverse case, where the pideer Epicadus heterogaster mimics an orchid so that insects come to t in search of nectar.Ĭanari birds are named after the islands. The brassia spider orchid looks like a spider, to fool the wasps. A species of wasp stings spiders and lay eggs on them. Some flowers look like bees to attract insects. We should remeber that flowers may have more colors and patterns in the ultraviolet spectrum that we cannot see but insect can (e.g. It's a balance for the flower, since it's costy to produce, also producing too much and there is no incentive for the insect to visit the next flower, too little and there is no incentive to visit.Ĭolors may also be a way to attract. Nectar is a sugary syrup manufactured by plants specifically and only for paying and fuelling animal polenisators (bees, hummingbird, etc.). Using animal is more efficient, flowers use nectar and colors to attract them. To some extent, selecting breeding is also found in nature, where generations of ancestral flowers were chosen by generations of ancestral insects of hummingbirds or other natural pollinators. This was investigated by Sir Huxley in the 1930s.Ĭhapter 3 - The primrose path to macro evolution Often, the rates of growth of different parts of an animal bear some simple mathematcal relation. But when there is a systematic increase of decrease in the frequency of a particular gene in a gene poll, that's exactly waht is mean by evolution.Īll puppies have similar faces becasue they all need to suck and for this it's not advantageous to have a long snout. There is no intrinsic tendency in gene polls for particular genes to increase or decrease in frequency. Each individual animal that we see in a population is a sampling of the gene pool of its time. Similarly, all breeds of dogs are modified wolves: not jackals, not coyotes and nt foxes. Horiculturalists have changed the wild cabage Brassica oleracea, over few centuries, into :broccoli, cauliflower, kohlrabi, kale, Brussel sprouts, spring greens, romanescu and other cabbages. As the Greek philosopher Heraclitus said "all is fluid, nothing is fixed".Įvolution of species can be shown by the artificial selection. This evolution is continuous and the definition of a species is just representative of a given population at a given time. After tens of thousands of years, the rabbits may have evolved in another population with different traits. The problem is that the definition of a species is not that easy. The same can be said of the rabbits we see, they are flawed deviations of the "ideal" notion of raabit. A triangle drawn in the sand is just the shadow of the ideal essential triangle. For Plate, the reality that we think we see is just shadows cas on the wall of our cave by the flickering light of the camp fire. Natural selection is most likely the predominant driving force.ĭawkins states tha the discovery of evolution was held back by the dead heand of Plato. The differen theories are natural selection, or "Lamarck's theory of "use and disuse" and the "inheritance of acquired charactistics". It is possible to make a distinction between the "fact" (or theorum) of evolution and the theory of what drives it. There is the famous Gorilla experiment, whne people watch a basketball film and look at the passes but they fail to see a Gorilla is crossing the scene. Psychological experiments have shown how little "eye-witness" testimony can be trusted. In science, things are just facts, that evidence confirms and that have never been disproven.Ī conjecture is a proposition that looks true but has never been proved, it becomes a theorem once proved.Įxample: The Goldbach Conjecture states that any even integer can be expressed as the sum of two primes.ĭawkins calls the theory of evolution a "theorum", something that cannot be proved like a mathematematical theorem. Mathematicians are the only ones that can strictly prove things. Influencial philosophers tell us we can't prove anyting in science. Watch the three episode series "The Genius of Charles Darwin" from Channel 4, 2008ĭawkins discusses here, what a theory is and what is mean by the theory of evolution.Ĥ0% of americans deny that humans evolved from other animals and think that we were created by god within the last 10000 years. Summay/notes on the The Greatest Show on Earth by Richard Dawkins
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |