Why are we humans? Please, 3Q

This is thanks to volcanoes and forests, 500,000 years ago, the earth was very cold, and at this time, volcanoes came to the rescue, and a lot of carbon dioxide rushed into the atmosphere, warming the climate, and humans survived, and earlier, forests could spit out a lot of water, absorb less water, and give us oxygen, so we owe it to them.

Hegel said that existence is rationality and that human existence is a necessity of biological evolution.

Because the earth is suitable for us humans to produce.

The Birth and Development of Mankind: Humans were born 5 million years ago. That is to say, 60 million years after the extinction of the dinosaurs, human beings were born Human beings are differentiated from the animal kingdom, and taxonomically, homo sapiens belongs to the subphylum Vertebrates, Mammalia, Primates, Anthropoids, and Hominis.

About 4.5 million years ago, humans and apes began to diverge, giving rise to Australopithecus ramanacus, which later evolved from Australopithecus australopithecus 2 million years ago, and then further developed into modern humans. Regarding the development process of human beings, it is generally divided into four stages: 1. The early ape-man stage.

It lived between 3 million and 1.5 million years ago, and already possessed the basic characteristics of humans, such as being able to walk upright and make simple gravel tools. 2. Late ape-man stage. About 2 million to 300,000 years ago, the body resembled a man, the brain was larger, and it could make more advanced paleolithic tools, and began to use fire, such as the Beijing ape man in Zhoukoudian, Beijing, China.

3. Early Homo sapiens (hominid) stage. Between 100,000 and 200,000 to 50,000 years ago, it gradually broke away from the characteristics of apes and was very close to modern humans, such as Neanderthals in Germany. 4. Late Homo sapiens (newcomer) stage.

About 4-50,000 years ago, the evolution of human beings at this time showed a significant acceleration, and the morphology was very similar to that of modern humans, and culturally, there were already the art of carving and painting, and ornaments appeared. For example, in 1933, the cave man on the top of Zhoukoudian Keel Mountain was discovered. At this time, primitive religions had already arisen and had entered a matriarchal society.

In the late Homo sapiens stage, modern humans began to differentiate and form, and spread throughout the world.

Nature has given the animals of ancient times, the predecessors of man, and the ancient apes. Through selection, there are human beings, and human beings are the "people" of the contemporary era after countless changes.

There are two theories in vogue now: First, man evolved from apes. Second, humans are derived from aliens through genetic variants, and why are there two theories? So far, there has not been a single fossil in the world that can show that man evolved from apes, and if the first one is correct, then there should be fossils in the world to confirm it, but it has not been found, and the first theory is also questioned.

Recently, a foreign scientist discovered a special skull that resembles a human skull, but it's not entirely human, and some scientists point out that it's a descendant of aliens and earthlings. It's still a tough puzzle to solve!

The world's population has exploded, and the number of people living has exceeded that of all the people who have passed away in the past combined—a saying that has been in vogue for many years. It is said that in the 70s of the last century, statistics showed that 75% of the total number of births in recorded history was born, and this theory was developed at that time. In 1995, demographer Carl Haub and his colleagues at the U.S. Population Advisory Bureau began calculating how many people have lived in the world since ancient times.

To calculate this figure, he needs to consider when the first humans were born, and calculate the population growth rate for different historical periods based on available demographic statistics. In 1973, the United Nations published a report entitled "Determinants and Consequences of Population Development Trends". Based on this report, Haub deduced that the first humans who appeared on Earth date back to 50,000 years ago, when there were only two people:

Adam" and "Eve". While it's hard to know how the population has grown since then, Haub has relied on statistics from the United Nations and other organizations to conclude that by 8,000 B.C., there were about 5 million people living on Earth. From 8000 BC to the rise of ancient Rome, population growth was relatively slow, with an average annual growth rate of less than one thousandth.

By the first year of AD, the world's population was only 300 million. Subsequent plagues claimed countless lives (the Black Death in the 14th century alone killed more than 75 million people). By 1650, the world's population had grown to only about 500 million.

But with improvements in agricultural production and sanitation, by 1850 the population had doubled to more than 1 billion. In 2002, the population of the planet had skyrocketed to 6.2 billion. According to the results of these figures, the number of people born on the earth from the beginning of human beings to the present is more than 106 billion, and there are only 6.5 billion people living on the earth today.

So, what will be the population in the future? At present, the population is growing at a rate of about 2% per year, which is 2% less than in the 60s, and it is reasonable to say that the global population will reach 8.9 billion by 2050. In addition, the United Nations is developing various population control plans to keep the global population at around 10 billion by 2200.

At this rate, it is unlikely that the total number of people living at any one time will exceed the total number of people who have ever existed on Earth.