What conditions do we need for life on Earth to grow indefinitely?

When we see the giant snake in The Scourge of Python and the Godzilla monster in Japan, we are obviously excited and shocked. At the same time, we are increasingly afraid: will animals really grow bigger and bigger without limit?

Take us as an example:

According to the investigation and research, human beings have lived on the earth for 4.4 million years. Over time, many different shapes and sizes of human beings have evolved. However, no one in the world is more than 10 meters tall.

There are certain restrictions on human body shape, and once adults, bones stop growing. That is to say, after a growth restriction point, we will not grow bigger, and in the long run, we will only have a smaller trend.
Human beings are a special group, so are all animals the same? Is animal growth restricted?

The answer is yes. Animals have a range of specific needs for growth, including food availability, nutritional value, temperature, natural predators, metabolic needs, and numerous other factors that drive their evolution in a particular pattern. Their growth is limited by nature.

External constraints

Every step in the evolutionary history of living things is based on millions of small mutations that occur in tens of thousands of generations. Each mutation leads to the size, shape, color and other biological characteristics we see today.
When it comes to animal size, many people will quickly think about the size of dinosaurs. The largest creature we have ever found is the fragile double-chambered dragon. The average adult weight is 180 tons, individual weight can reach 220 tons, body length is more than 50 meters, height is 10-15 meters, living in the late Jurassic.

The environment during the dinosaur period was very different from what we now know. At that time, the atmosphere was rich in carbon dioxide, and plants grew in large quantities, resulting in higher oxygen content.

This allowed the dominant dinosaurs on the planet to have few natural enemies, except other carnivorous dinosaurs, and to increase their size in proportion to the material needs available. This is one of the reasons why animals grow bigger: they have plenty of food and little competition.

Giant organisms tend to be highly adaptable in the short term, but in the long evolutionary period, most of them are facing many unavoidable challenges.
To survive better, giant animals must have larger habitats to prevent competition for food, but this also makes them more susceptible to disease and unable to mate.

Although being large means being less threatened by predators, other aspects of life may make it difficult for them to survive.

But now, our world has changed a lot, with millions of different species, more complex ecosystems and food chains, and the impact and destruction of human beings on ecosystems and the global environment, it is easy to understand why animals have no chance to grow to incredible size.

In the increasingly limited wild space, animals have more opportunities to contact predators, making them gradually submit to climate change or human impact.

Although this is a depressing reason, there are other factors that affect body size.
The evolutionary trend of many species is to provide organs of a certain size and function to support the established body shape. This is determined by biological evolution and genetic selection. This is why most species have a range of growth.
Natural limitations impose an upper limit on the size of most species, but there are exceptions. Some organisms are not very large in size, but their growth never ends.
Compared with dinosaurs, many animals may not grow to huge sizes, but they do continue to grow throughout their lives.
The most common examples of this phenomenon are sharks, crocodiles, kangaroos, snakes, crayfish, iguanas, many lizards, turtles, lobsters and octopuses. This endless growth is called "unlimited growth".
Adolescence is an incredible period of growth and change for humans, and hormonal fluctuations in the body can be extreme.
During this period, estrogen produced by the body (male and female) causes the growth plates of our bones to fuse together, so we tend to stop "getting higher" when we reach adult size.
When we want to grow bigger and live longer, we naturally think of "aging". Human beings will age, organ system will gradually collapse, and cells will mutate, which will reduce the efficiency of the body. This is aging.
In these "unrestricted growth" animals, researchers have found that aging is insignificant for them, such as turtles, whose aging rate is very slow, and the cell composition and structure of 100-year-old turtles are basically the same as that of 20-year-old turtles.
On the other hand, we have not found sharks as big as aircraft carriers, nor octopuses as big as aircraft, because they grow very slowly, just like a tree adding only one ring to its trunk every year, we only see a representation of a certain period in the history of evolution.
Because it is impossible to evolve into a Big Mac due to the limitations of many objective problems, we believe that the size of many animals is limited.
However, marine mammals may break the spell. If a giant animal like King Kong does exist in movies, it is most likely to live in the ocean like a blue whale. Scientists believe that blue whales can grow bigger, even more than 200 tons.
This is because the ocean has huge space to carry giant creatures like blue whales, and the buoyancy of water helps animals support their body weight and relieve the pressure on muscles and bones.
However, due to the limitation of food sources, blue whales will not grow larger endlessly. It is for this reason that human beings are always fearful and awed of the sea.