Do you really know our closest primate relatives?

Looking at the natural world today, if you see creatures that have grasping hands like us, you will definitely think of primates, our closest relatives. We often associate apes and monkeys together because they are both primates, so we have a natural affinity for primates. But can you really tell them apart?

For many people, the image of monkeys that most deeply impressed them is probably the image of Sun Wukong in Journey to the West. The prototype of Sun Wukong is a macaque, and his image is like this.

Figure 1 Sun Wukong (Photo from the Internet)

As for the image of ape, the most impressive one is probably the affectionate and righteous King Kong in the movie "King Kong".

Figure 2 King Kong (Photo from the Internet)

Have you discovered the difference between apes and monkeys in these images?

There are four main types of modern apes: great apes, brown apes, black apes and gibbons. The first three types of large apes are generally called great apes. They are larger than monkeys and have a more recognizable appearance, making them difficult to confuse with monkeys. Gibbons, as the smallest and most primitive of the ape family, usually weigh no more than 10 kilograms, which is similar to monkeys and can be easily confused.

Are you still confused about the difference between apes and monkeys? Test your eyesight by observing the difference between the two different primates in the picture below:

Figure 3: Long-tailed langur on the top and northern white-cheeked gibbon on the bottom

Photography: Yang Jinsong

Maybe you have already noticed the difference in the tail. Monkeys have tails, but apes don't. Scientific experimental data also proves that apes are closer to humans in terms of DNA and brain capacity. So the view in the theory of evolution that "humans evolved from apes" is not without basis. Let's take a look at the differences between the characteristics of these two primates today.

(1) Monkeys have tails while apes do not, so monkeys are tailed primates and apes are tailless primates;

(2) The arms of apes are longer than their legs, while the arms of monkeys are generally of the same length as their legs. The range of motion of the upper arms of apes is significantly greater than that of monkeys. For example, when walking upright, apes can raise their upper arms, while monkeys cannot (except for spider monkeys).

(3) Apes can walk in an upright posture, while monkeys walk on all fours. Therefore, when monkeys walk on all fours, their hips and shoulders are in the same horizontal plane, while the shoulders of apes are obviously higher than their hips.

(4) The brain capacity and intelligence level of apes are generally more developed than those of monkeys; apes are also closer to humans in other aspects such as physiology, morphology, and behavior than monkeys;

(5) Apes reach sexual maturity later than monkeys and have a longer reproductive interval, so the reproductive capacity of apes is not as strong as that of monkeys.

Figure 4 From left to right are the skulls of adult lemurs, green monkeys, gibbons, baboons, chimpanzees and humans (Image source: Internet)

Figure 5 Primate skull anatomy, from left to right: chimpanzee skull, human skull, gorilla skull (picture from the Internet)

When it comes to intelligence that is closer to that of humans, it has to be the orangutan. From the contrasting features of the skulls shown in the above pictures, do you find that the skulls of humans and orangutans are also closer?

Many studies have shown that primates have developed brains, complex cognitive abilities, and stable social structures. Their behavior, organizational structure, physiological and metabolic characteristics, and even the diseases they suffer from are strikingly similar to those of humans. From the perspective of molecular genetics, the similarity between monkey genes and humans can reach 93%, while the similarity between orangutans is as high as 98%-99%. In addition, the three great apes have only one more pair of chromosomes than humans.

Figure 6 Chimpanzee intelligence experiment (Image source: Internet)

Perhaps everyone has seen an experiment on chimpanzee intelligence, where a series of numbers or patterns are quickly displayed on a screen, and then the process is repeated in sequence. Through stress training by feeding food, chimpanzees can remember the position and order of nine numbers within one second. Obviously, chimpanzees are better than monkeys in this intelligence test.

Are you thinking: It seems that it is difficult for humans to complete this intelligence test in one second. Is human intelligence inferior to that of chimpanzees? No, the experiment only shows that chimpanzees have stronger instantaneous memory. However, humans have a larger brain capacity and are good at more complex brain activities to achieve the preset goals, which leads to creativity and the emergence of various fields such as science and technology, literature, and art in human society. The reason why humans can become the most advanced life on earth is precisely because of their infinite creativity.

(Thanks to Researcher Wu Dongdong from Kunming Institute of Zoology and Professor Fan Pengfei from Sun Yat-sen University for their help with this article)

Author: Yang Jinsong