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The evolution of species
Darwin was a British scientist who laid the foundations of the theory of evolution and transformed the way we think about the natural world.
The study of evolution provides a foundation for our understanding of the history of life.
Evolution—which can be defined briefly as descent with modification—provides us with the scientific framework to investigate how species change over time and how various groups of living organisms relate to one another. The process of natural selection explains one of the ways in which animals evolve; it provides a mechanism by which species can change over time.
Natural selection is an evolutionary mechanism by which traits unsuited for a particular condition are diminished while traits better suited for those conditions become established in a population. Natural selection is founded on a handful of simple concepts—the variation of traits within a population, differential reproduction, and heritability of traits.
Darwin’s concept of evolutionary adaptation through natural selection became central to modern evolutionary theory, now the unifying concept of the life sciences.
The natural diet of different species
- Herbivores eat only plants – egs cows, buffalo, etc.
- Omnivores eat both plants and animals – egs baboons, rats, cockroaches, people, etc.
- Carnivores eat only animals – egs cat family (wild cats, lions, leopard, tigers, domestic cats, etc.) and dog family (wolves, foxes, jackals, wild dogs).
- Decomposers are microorganisms – which convert complex substances and compounds into simper substances and return the simplified gases to the atmosphere and the rest of organic matter to the earth, thus increasing its fertility. Therefore they clean the earth of all its waste. Eg fungus
- Detritivores are organisms – which consume the dead and decaying matter, digest them into simpler substances, and then excreting them as organic matter into the soil thus increasing its fertility egs earthworms, millipedes, centipedes ‘detritus’ mean ‘decaying’.
Geographical Origin of Dogs
According to most experts, all modern dog breeds are posited to have originated from Southeast Asia. There, thousands of years ago, humans interacted with local grey wolf populations and eventually domesticated them. Humans used artificial selection, or selective breeding for certain traits, to mould dog species for different utilities. Centuries of artificial selection have given us modern dog breeds and continue to create new dog breeds today
The earliest association between modern pets and humans
Domestication (from Latin domesticus) is the process whereby a population of living organisms is changed at the genetic level, through generations of selective breeding, to accentuate traits that ultimately benefit humans.
A usual by-product of domestication is the creation of a dependency in the domesticated organisms, so that they lose their ability to live in the wild.
It differs from taming in that a change in the phonotypical expression and genotype of the animal occurs, whereas taming is simply the process by which animals become accustomed to human presence.
In the Convention on Biological Diversity, a domesticated species is defined as a “species in which the evolutionary process has been influenced by humans to meet their needs.” Therefore, a defining characteristic of domestication is artificial selection by humans.
Humans have brought these populations under their control and care for a wide range of reasons: to produce food or valuable commodities (such as wool, cotton, or silk), for types of work (such as transportation, protection, and warfare), scientific research, or simply to enjoy as companions or ornaments.
The domestication of dogs provides an example:
It is speculated that tamer than average wolves, less wary of humans, selected themselves as dogs over many generations.
These wolves were able to thrive by following humans to scavenge for food near camp fires and garbage dumps, which gave them an advantage over more shy individuals.
Eventually a symbiotic relationship developed between people and these proto-dogs.
The dogs fed on human food scraps, and humans found that dogs could warn them of approaching dangers, help with hunting, act as pets, provide warmth, or supplement their food supply.
As this relationship progressed, humans eventually began to keep these self-tamed wolves and breed from them the types of dogs that we have today.
The effects of domestication on breed development
The selection of animals for visible “desirable” traits may make them unfit in other, unseen ways. Eg the English bulldog is very often not able to breed or give birth unassisted.
Prone to breathing problems; some have small windpipes as well. Also poor eyesight, cherry eye, very susceptible to heatstroke in warm weather or hot rooms and cars. Very cold sensitive. Prone to mast cell tumours. Birth defects are common in some lines. Susceptible to skin infections, hip and knee problems. Prone to flatulence, especially when fed any other type of food other than their regular dog food. Puppies are often delivered by caesarean section.
The consequences for the captive and domesticated animals were reduction in size, piebald colour, shorter faces with smaller and fewer teeth, diminished horns, weak muscle ridges, and less genetic variability. Poor joint definition, late fusion of bone structure, hair changes, greater fat accumulation, smaller brains, simplified behaviour patterns, extended immaturity, and more pathology are a few of the defects of domestic animals.
All of these changes have been documented in direct observations of the rat in the 19th century, by archaeological evidence, and confirmed by animal breeders in the 20th century
One side effect of domestication has been zoonotic diseases.
- Cattle have given humanity various viral poxes, measles, and tuberculosis
- pigs and ducks have given influenza
- horses have given the rhinoviruses
Humans share over 60 diseases with dogs!