What caused giraffes to evolve and how did giraffes evolve

To put it simply, it is the survival of the fittest, the survival of the fittest.

When organisms reproduce their next generation, they will select individuals with strong bodies and good genes, which is called sexual selection. This is also common in humans, and women mostly prefer men who are physically strong. In a giraffe population, there is an average length of the neck in a historical period, but there are certainly higher than average and smaller than average.

According to the normal distribution, both those who are longer than the average and those who are shorter than the average account for the minority, and those who are near the mean account for the vast majority. During the feeding process, the leaves that can be reached by the average length of the giraffe must be eaten more, and the competition for food at this height will be more fierce because everyone can reach it. However, individuals who are significantly higher than the average can eat most of the leaves that cannot be eaten in the group, so that they can have more food, and they can grow stronger and healthier, becoming the most "charismatic" and competitive individuals in the population.

When it comes to breeding season, female giraffes obviously prefer giraffes with strong necks, and giraffes with necks have a chance to breed more offspring. The giraffe near the average obviously can't compete with the long-necked, while the short-necked one eats less than others and is smaller than others, and the chance of breeding is much smaller than that of other individuals. This happens again and again in every breeding season and in every generation of giraffes.

As a result, the genes of long-necked giraffes account for an increasing proportion of the population, and the average value of the necks of the entire giraffe population is also being raised, which in turn strengthens this culling mechanism. So after a considerable period of time, the giraffe's neck will grow longer and longer.

Giraffes mutate and develop long necks, which have an advantage in the struggle for survival, both in obtaining food and in fighting predators, so the mutation of long necks can be preserved and passed on to offspring.

What causes a giraffe's neck to lengthen? Genes that promote the evolution of organisms.

Giraffe habits: Giraffes live in arid and open savanna areas and live in groups. The number of colonies varies widely, from 2 or 3 to more than 40 and sometimes more than 70.

Their diet consists of a variety of tall leaves and branches, especially leguminous trees.

They are used to eat most of the day, especially in the morning and afternoon, when they are almost always eating. Due to their long legs and neck, they are able to reach leaves up to 6 meters above the ground. Although they eat tender plant foods, giraffes drink water every day.

Features of giraffes:

The giraffe is a cervid that lives in Africa and is loved by people for its docile personality and beautiful and elegant appearance. The giraffe's main attraction is its long neck and beautiful fur.

How long is a giraffe's neck? Adult giraffes are between meters tall and the tallest is up to meters. The giraffe's height is mainly supported by its long neck, which is a meter long, accounting for almost half of its height.

It is quite fair to say that the giraffe is the tallest animal in the world.

The evolutionary process of giraffes is as follows:

1. The giraffe family is the most unique type of artiodactyl, the teeth are the primitive low-crown type, can not be the main diet of grass, can only feed on leaves, the tongue is long, it can be used for feeding, there are short horns on the head, and the horns are covered with hairy **. There are only 2 species of giraffe in Africa, and the prehistoric distribution is more extensive, which can be divided into the subfamily Gulinidae, the giraffe subfamily and the subfamily Cirva.

2. According to the fossil record, giraffes were first differentiated from cervids in the early Miocene. The earliest giraffe fossils are climacoceras and canthumeryx. Later, it evolved Gulin, an early Miocene giraffe ancestor with short horns and short necks.

By the late Miocene, Gurin evolved into Satsuma. In the Pliocene, the satsuma beast diverged into the okapi and the early modern giraffe.

3. The giraffe subfamily is a giraffe that lives in the savanna area, because the trees in the savanna are mostly umbrella-shaped, and the leaves are concentrated in the upper layer, the giraffe silver friend has evolved a longer neck and limbs, and can eat the leaves. There is only one species of giraffe in the subfamily Giraffe of the Flap Acacia subfamily, which is widely distributed in the savanna region of Africa, and is the tallest living animal and one of the most familiar African animals.

Giraffes

The giraffe, belonging to the phylum Chordates and the Giraffe family, is a ruminant cloven-hoofed animal that grows in Africa, and its Latin name means "leopard-patterned camel". They are the tallest surviving terrestrial animals in the world. The protection level is vulnerable.

Giraffes did not evolve. The giraffe's size is very special, and its existence requires a very complex and irreducible organizational structure at the same time, and neither of them can be completed through evolution.

First, a super big heart. A giraffe's long neck necessarily requires it to have a large heart in order to carry blood to its head. However, it is well known that many people in the world today do not have a blood supply to the brain, but their hearts and their offspring have not enlarged.

Second, the perfect solution to the danger of violent death. Because the neck is too long, it is necessary to have extremely high blood pressure to pump blood to the brain. But the question is, what to do with giraffes drinking water?

With such high blood pressure, when they lower their heads, the blood will inevitably burst through the blood vessels in the brain and they will die violently. But the amazing thing is that the giraffes have a special reticular hemangioma in the back of their brain, and when they bow their heads, this tissue buffers the flow of blood to the brain, preventing sudden death. So how did this organization evolve?

When giraffes can't go without drinking water, in other words, whether they have this organization or not directly determines whether they can survive or not, and this organization is a prerequisite for their survival, and it cannot withstand the long evolutionary time.

Third, resilience**. Or because of high blood pressure, giraffes are bound to be difficult to stop bleeding once they bleed, but fortunately they are very tough. We often see lions trying to prey on giraffes, but their claws can't pierce the giraffe's **.

In summary, the giraffe's long neck determines that it must have many complex irreducible organizational characteristics. This suggests that it was designed, not evolved.

The reason why a giraffe's neck is so long is because of the result of natural evolution. In the beginning, due to the increasing number of herbivores on the earth, the grass was no longer enough to eat, so the giraffe tried to eat the leaves on the trees, and to eat these leaves, they had to stretch their necks to eat, and as the trees grew taller and the giraffes wanted to eat more leaves, they had more time to stretch their necks and use their necks. Giraffes have gradually lengthened their necks in order to adapt to the needs of production in the course of tens of millions of years of evolution, while those short-necked giraffes that cannot eat leaves have been eliminated by nature.

Giraffe's Neck The giraffe's neck has become that long mainly as a result of natural evolution and selection. In the early days, giraffes' necks were not so long, and they were long and short, and later in the drought period, many of the plants on the ground died, and the remaining grass was eaten by other animals. In order to survive, giraffes have to eat the leaves of trees, and this is when short-necked giraffes show a disadvantage, they can only eat the leaves of low trees, and then they are eliminated when they do not have enough to eat.

As a result of natural evolution and selection, those giraffes with longer necks can eat higher leaves, and in order to survive for a long time, they try to stretch their necks to eat higher and more leaves, so that their necks grow and develop again and become longer and longer, and after inheritance from generation to generation, the genes for long necks are determined. The giraffe's longer neck looks like the result of the giraffe's efforts to survive, but it is actually the result of natural selection.

Of course, this is only the speculation of modern scientists, and there is no substantial evidence for the time being, and scientists have been debating why the giraffe's neck is so long. There is also a saying that the giraffe had such a long neck when it appeared, thinking that the genes of this species were originally like this, and it had a long neck when it was just created, after all, the neck of the giraffe is indeed too long, and it is easy to evolve the neck into a few centimeters or more than ten centimeters, and it seems a little magical to evolve a few meters, so there is a saying that the gene is destined to do so.

The evolved length of the giraffe's neck is the result of natural selection. The ancestors of giraffes were herbivores that lived on the ground, and because of geological and environmental changes, plants on the surface began to grow upwards, while the ancestors of giraffes could only evolve to grow their necks to obtain food in order to survive.

The long neck of the giraffe is naturally screened out, and the giraffe with a short neck can't eat food so it disappears, and those who stay are all long-necked, natural selection, survival of the fittest.

is the result of natural selection. Giraffes often stretch their necks to reach high enough for plants because of their limited food in their previous environment, so their necks become longer and longer.

Why Do Giraffes Have That Long Necks?

Behavioral habits. Giraffes have a very keen sense of hearing and vision. The eye can see what is behind them, but they rarely make sounds.

Male giraffes are more "belligerent", fighting for a long time, surrounding each other, like two people fighting each other, and neither of them will leave first.

Giraffes get very little sleep, generally only two hours a night, and sleep can sometimes put them at risk. Giraffes sleep standing most of the time, usually standing and sleeping in a state of false sleep. Because the neck is too long, giraffes often rest their heads against branches when they sleep so that their necks are not too tired.

When giraffes enter the sleep phase, they, like elephants, need to lie down and rest, which lasts about 20 minutes. Giraffes rarely make sounds, and they can quickly search for infrasound waves that humans can't hear.

Food habits. Giraffes live in packs. Sometimes mixed with zebras, ostriches, antelopes, diurnal.

He has a keen sense of smell and hearing, is alert and timid, usually walks leisurely, but runs quickly (up to 70 km/h). Foraging in the morning and dusk, in the wild, mainly eating all kinds of leaves, especially the leaves of the genus Mimosa, a giraffe can ingest 63 kg of leaves and twigs per day. Thirst-tolerant, can go a year without water when the leaves are well hydrated.

The habits of giraffes.

52kexue by - 2006-5-16 9:05:53

Kima monkey, body length 52-70cm, tail length 6-7cm, male weight of about 25kg, female weight of about 12kg, national second-class protected animals.

Giraffes are found in sub-Saharan Africa.

Giraffes live in savannahs and forest fringes. It is the tallest animal in existence. Clusters, sometimes mixed with zebras, ostriches, antelopes, diurnal.

Keen to smell and hear, alert and timid, usually walks leisurely, but runs quickly (up to 56 km/h). Foraging in the morning and dusk, mainly eating all kinds of leaves, thirst-resistant.

The breeding period of giraffes is not fixed, the gestation period is 14 to 15 months, each litter is born, the age is sexually mature, and the lifespan is about 30 years.

Giraffe family: There are only 2 genera and 2 species in this family. They are found in most of sub-Saharan Africa.

They have long legs, long necks (but still 7 cervical vertebrae), large ears, large eyes, long tongues, and the ability to curl and extend. The feet are broad, with two toes and hooves, and the transverse toes are underdeveloped. Stomach 4-chambered, ruminant, without gallbladder.

The giraffe walks slowly, gracefully, and with a distinctive gait, alternating between the left forelimb, the left hindlimb, the right forelimb, and the right hindlimb, which looks very solemn and elegant.

In the wild, giraffes feed on leaves, and a single giraffe can ingest 63 kg of leaves and twigs per day. Giraffes walk with a leisurely gait. When walking, one front and rear limb moves forward and the other front and rear limb touches the ground.

This is a common locomotion used by large quadrupeds, such as elephants. But when a giraffe is attacked by an enemy, it can run at a speed of 60 kilometers per hour, which is as fast as our car! But the giraffe's heart is too small for it to run long distances.

When threatened, the giraffe's defense is to kick the enemy in vital places with its feet, a kick is enough to shatter the lion's skull. Giraffes sleep the shortest amount of sleep per day of any mammal. It's usually only between 20 minutes and two hours, and guess how it sleeps?

It is able to sleep with its eyes open. On the top of each giraffe's head, there will be short horns, most giraffes only grow a pair of horns (there are also long horns, very rare), which are used for play, and the real place to fight is its powerful hind legs, these four legs can kick lions, leopards and other predators to the ground, and some can even kick predators to death.