Many animals born, both visual and hearing can not function properly or, worse, until 1-2 weeks after birth, some animals (such as dogs) and visual and hearing to be ready to work after a few weeks to fully mature, why natural selection would allow this?
Early VS late
In the process of evolution, the species to survive and reproduce, each developed a best way to adapt to the environment, mammals have, too, in the production of cubs when they face a second election issue – in the end is to choose a longer pregnancy time, better physical development and fertility, the offspring of the whole organ function better? Or choose some shorter during pregnancy, and then give birth to premature or even part of the development has not been completed, it needs more care of future generations?
Deer and cattle are born when the extreme mature representatives. A cow is nine months of pregnancy. Newborn calf weighs about 25 to 45 kilograms (55-99 pounds), and their brain has fully developed. Their senses to see or hear can be effective. Most importantly, they can quickly running, you can keep up with the pace of the entire herd.
Can give birth to relatively mature development, can come down to earth running offspring, biologists call such animals as “precocious species.” Here “premature” to use the word just like we talk about the level of development especially those early mental and psychological maturity far beyond the actual age of the child is no different. Clearly, a need to escape predators for a species is related to the running ability can not be the key to survival factors, and thus born of the development of more mature when it is necessary.
The wide variety of canids, including dogs, represents the other extreme. In the wild, dogs are to survive by hunting. Heavily pregnant bitches will slow down the speed, so running them more difficult to catch fast prey, therefore, difficult to complete them in the population that completed the task of hunting. This means quickly to the dogs born from the womb more favorable survival.
In addition, after hunting (hunting between the two may be a few days time interval), the female dog is almost nothing, so the bitch will have more time to take care of helpless young. When she was struggling to chase their prey for food outside, the cubs can not run around safely parked in the nest.
Dog’s pregnancy is relatively very short, only about two months – an average of 58-63 days – and thus the result is a very helpless puppy Aberdeen. Biologists call this birth immature, dependent offspring of the species known as the “late-maturing species”, this is from the Latin root word of “care, feeding, nourishing” the word evolved. This term refers specifically to the larvae of these species need a long period of feeding and care.
Blind and deaf to protect
Puppies many of the key organs (including brain) are not fully developed at birth, but they will within a few weeks after the birth of puppies speed development. Their eyes, too, the puppies are born with eyes closed, because they are still growing is still extremely fragile eyes, eyes closed against the need soil, gravel and pathogens. In addition, the eye exposed to the light too bright before, it tends to hurt their delicate function of photoreceptor cells and eyes.
Most of the big dog around two weeks opened my eyes, even so, their eyes still not perfect development, function and did not reach perfection, but also take several weeks to fully mature eye, reaching the level of normal vision.
With eyes closed, like the dog blocking the ear canal at birth is almost the truth. Relatively quiet for the hearing system development is very important, because a strong voice will damage the dog’s ear structure. Hearing dogs are fragile in the system has not fully developed, if they are forced to respond to your voice, it is likely they will be a huge set of auditory organ damage.
Dog ear open and eyes open, almost simultaneously, the same way, even if they are open ear canal hearing systems still need several weeks to well-developed. But most of the ear canal open, just a week, hearing dogs will be completely free and extremely sensitive to the.