There are no penguins in the Arctic. Is it because it's not cold enough?

Review expert: Cai Dawei, Professor of Archaeology, Jilin University

I'm sure everyone has heard this brain teaser: Why don't polar bears eat penguins? The reason is simple: one is in the Arctic and the other is in the Antarctic, which are 108,000 miles apart and have nothing to do with each other.

So, let’s talk about this question seriously: Why are there no penguins in the Arctic and no polar bears in the Antarctic?

Source: Wikipedia/Jerzy Strzelecki

Antarctica: A large isolated island

I believe everyone has heard of the theory of plate drift . In fact, many of the plates that we see on the map today, thousands of miles apart, were connected or even part of the same thing a long time ago.

Many geologists combined the characteristics of rock landforms, observed the paleontological fossils that have been unearthed, collected and sorted out the distribution of basaltic volcanic rocks, and finally found that the rocks in Antarctica and its surrounding areas (seas) have certain similarities with the rocks from the Precambrian to the Mesozoic period. The unearthed paleontological fossils indicate that the relevant organisms lived from the Paleozoic to the Mesozoic period, and the widely distributed basaltic volcanic rocks come from the Jurassic period.

Combining the above information with evidence such as the morphology of the continental margins, geographers can basically determine that according to the theory of continental drift, there was a huge primitive continent in the Southern Hemisphere. This primitive continent has undergone a long geological evolution and gradually formed multiple geographical regions including Madagascar, South America, India, Africa, Australia, New Zealand, Antarctica, etc. Geographers named it "Gondwana".

Schematic diagram of Gondwana about 420 million years ago, with the center of view being the geographic South Pole

Source: Wikipedia/Fama Clamosa

Some scholars believe that the time when local regions began to split may be impossible to determine, but this does not prevent the mainstream academic community from identifying the time period when the "Gondwana" began to split: the Jurassic period .

During this period, the northwest coast of Australia experienced rifting and seafloor spreading, while Brazil, southeast Africa and Antarctica experienced widespread basaltic eruptions. The separation of India and Antarctica began in the Late Jurassic or Early Cretaceous. During the Cretaceous, the spreading axis extended westward through the South Pacific, eventually separating New Zealand, West Antarctica, East Antarctica and Australia. In the Early Tertiary, geological movements caused the plates to continue to split, forming Australia and East Antarctica. After entering the Tertiary, the New Zealand Trough began to bend and the Alpine-type faults began to become active.

The final separation of Antarctica was completed in the mid-Tertiary period, when South America separated from the Antarctic Peninsula. This separation led to the development of the Antarctic Circumpolar Current, and the development of the modern ice sheet can be roughly traced back to that period.

Orthographic image of Antarctica

Source Wikipedia/Dave Pape

It can be seen that Antarctica had already become a large isolated island about 23 million years ago. This also prevented many terrestrial mammals from migrating to Antarctica from other continents. From the size of the body, it is not difficult to find that the ancestors of penguins were able to fly across the sea to Antarctica. In other words, there are no bears in Antarctica. The fundamental reason is that geological movement has led to geographical isolation, which has hindered the exchange of species between different continents.

The demise of the great auk

There are penguins in Antarctica, so are there no birds in the Arctic? In fact, the Arctic not only has birds, but also once had its own penguins: the great auk .

The Great Auk belongs to the family Pinguinidae in the order Charadriiformes, and its scientific name is Pinguinus impennis. Pinguis in the genus name means "fat man" in Latin.

Specimens of the Great Auk and its eggs

Source: Wikipedia/Mike Pennington

Similar to penguins, the great auk has acquired the ability to swim during its evolution. In order to hunt, they can even dive dozens of meters underwater. The great auk lives in a wide range of areas, and people can find them in the vast Atlantic Ocean and even New Zealand.

Once upon a time, Greenland was also a paradise for the great auk. However, due to excessive hunting by humans, the great auk became extinct in the 19th century. The reason why penguins still exist in Antarctica is probably because humans did not have the ability to cross the sea to hunt penguins when they were not respectful of nature.

Painting depicting a great auk colony

Source: Wikipedia

If the absence of polar bears in Antarctica is God's will, then the absence of penguins in the Arctic is undoubtedly a man-made disaster. The disappearance of the great auk fully demonstrates the brutal intervention of humans on the environment and creatures, and together with many species that have also died out due to humans, it has sounded the alarm!

Behind the cute appearance

Why do penguins look like they are swaying when they walk and polar bears look cute when they sit down to rest? In response to this, biologist Carl Bergmann proposed the famous Bergmann's Law in the 19th century, which roughly states that the same species (or species with a certain kinship) in different regions will be larger and rounder in size as the environment they live in becomes colder.

Bergman believes that there are two reasons for this phenomenon: first, the cold environment will slow down the growth of homeothermic animals and delay their sexual maturity, which will make the individuals have a longer development time, so the volume is relatively large; second, from a physics point of view, at a certain temperature, the volume of an object is certain, the smaller the surface area, the slower the heat dissipation.

Polar bear source: Wikipedia/Steve Amstrup

Biologist Joel Assaf Allen's research also found that the colder the living environment of the same animal, the shorter its limbs and appendages (ears, tail, etc.) tend to be.

This is because the limbs and appendages of animals are like heat sinks in physics, which greatly increase the heat dissipation area of ​​the body. Therefore, animals with better heat preservation ability (poor heat dissipation ability) tend to be larger and fatter, with short limbs and appendages, which leads to the appearance of animals living in the North and South Poles not being so angular.

There are no penguins in the Arctic and no polar bears in the Antarctic. This phenomenon, which is regarded as common sense by everyone, has such a rich evolutionary process behind it. If you continue to study this problem and learn to ask more questions, you will definitely gain more and deeper insights even in your daily life.