It’s often hard to separate the fact from the fiction, but the following five widely believed statements are in fact, fiction
1. Animals have four legs
Although many animals walk on all fours, the front limbs are technically arms with shoulder and elbow joints. Four-legged animals only have two knee joints found in the rear two limbs. Mammals began to evolve from four legged reptiles 285 million years ago, and the earliest mammals are thought to have been weasel-like mammals that were nocturnal. As time progressed and mammals became more adapted for movement, with the inward bending knees complimenting the outward bending elbows. These two joint types were the key to early mammal movement.
2. We don’t know if the chicken or the egg came first
This popular paradox actually does have an answer; it’s the egg. Reptiles and amphibians evolved before birds, so the egg came millions of years before the chicken walked the Earth.
The earliest dinosaurs laid eggs, beginning 250 million years ago. Birds only began to take flight around 66 million years ago, a whopping 185 million years after the first dinosaurs emerged. There were flying reptiles, but these are not considered true dinosaurs. Although they were able to fly and even look similar to modern birds, enormous pterodactyls were not ancestors of birds.
Many small terrestrial dinosaurs had feathers, in fact some scientists think most dinosaurs were feathered rather than scaly. After most of the dinosaurs died out, the small surviving reptile species eventually evolved into birds, like chickens.
3. Dog hearing is 10 times better than humans
The saying goes that dogs hear sounds 10 times louder than humans can, but in reality it’s closer to four times louder. They can also hear higher pitched sounds than us.
Wolves are the ancestors of domestic dogs, and wild wolves rely on hearing sounds over long distances. Loud sounds like sirens or fireworks don’t exist in nature, so dog hearing evolved without the risk of hearing damage. Dog ears are also designed to amplify sounds with their curved shape, and the ears are controlled by at least 18 muscles to help detect distant sounds.
Humans can hear sounds with frequencies from 20 hertz to 20 kilohertz. Frequency is commonly known at pitch, and 20 kilohertz is around the frequency of a rat squeaking. Dogs are able to hear sounds with frequencies of up to 60 kilohertz, which is up to three times as high as sounds humans can hear.
4. Squirrels plant trees by forgetting where they hide nuts
Both red and grey squirrels can remember locations of hidden nuts for at least 20 days, possibly up to 62 days. To embed the position of a stash of food in their brain, squirrels stand up and look around and scan their surroundings.
It is fair to say that although squirrels do remember where their food is stored, many trees grow from buried seeds left by these burrowing mammals. Squirrels cache more food than they can eat to ensure they survive through the winter. This is a role that squirrels play in their ecosystem, and help disperse seeds in the same way bees pollinate flowers.
5. Gannets are greedy
Although they are famous for guzzling food, gannets don’t deserve their greedy reputation. This idea has grown from how gannets behave when they first leave the nest. These birds nest on cliffs overlooking the sea. Young gannets feed for 13 solid weeks after hatching, and once they are big enough to fly they dive off their cliff top roost into the water below. The beefy youngsters are too heavy to take off initially, as they fed continuously to gain enough body mass to survive. Newly fledged gannets have to float on the ocean’s surface until their excess fat has burned off.
Adult gannets can dive into the water from a height of 30 metres (100 feet) and hit the surface at 100 kilometres (60 miles) per hour. They are incredibly adapted for such extreme dives, and dislocate their wings upon impact to prevent them from breaking. A gannet’s face and chest are even cushioned with in-built airbags to prevent injuries.
Image from flickr.com/photos/emyanmei