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Every living thing can trace its ancestry back to a common bacterium -

Around four billion years ago there lived a microbe called LUCA, the Last Universal Common Ancestor. Every living thing can trace its ancestry back to LUCA.

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Some animals are more closely related than you might think -

Bears, seals, and dogs are closely related carnivores but are on a different branch of the evolutionary tree to cats and hyenas. 

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The earliest mammal offshoot from the reptiles -

The platypus is the earliest mammal offshoot from reptiles. An indicator is that it lays eggs but produces milk just like other mammals.

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Lip twitching -

Lip twitching when angry is an evolutionary leftover. As with humans, this behavior can also be seen in wolves, bears, and chimpanzees.

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Squids lost their shells and became more agile to escape predators -

The ancestors of modern squids were once large and slow, with thick shells. As predators evolved to become better at capturing and crushing them, smaller, faster squids were able to escape and reproduce. Eventually these squids began losing their shells to prioritize speed and agility.

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The beaks of some birds develop due to diet -

Charles Darwin studied finches on the Galápagos Islands, documenting his theory of natural selection. Due to a number of factors, such as food availability, competition with other birds, and resource limitations, there are now over 15 species of finch found on the Galápagos.

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Snakes with hip bones -

Did you know that some snakes have hip bones, which demonstrate they once had four legs like their close cousins, lizards.

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Whales and dolphins once had legs -

Some whales and dolphins have small bones that occasionally appear as tiny rear flippers. This shows they once had back legs and that their ancestors walked on land. 

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Birds and crocodiles are related -

Birds evolved from dinosaurs, and both are descended from reptiles. This means the closest living reptilian relation to a bird is the crocodile.

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The elephant's trunk -

An elephant's trunk is a great example of evolutionary development. The trunk is an extended nose that is fused with animal's top lip. This lengthened as the elephant's ancestors became taller. With its heavy head, they needed an easier way to reach the ground.

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Eyeless creatures -

In the process of evolutionary change, you either use it or you lose it. This is so true of a group of cave-dwelling crustaceans. These crabs and shrimp live underground where there's no light. As a result, they've gone completely blind. 

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To guarantee survival of their species -

Because of evolution, many animals lay hundreds of eggs to ensure that some reach adulthood. Just imagine if all tadpoles survived. The world would be packed with frogs!

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A bird with teeth -

Birds haven't had teeth for 70 million years, but researchers have found them in the embryos of mutant chickens. It's believed that chickens rid themselves of teeth in order to develop beaks.

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Anteaters and their noodle-like tongues -

Anteaters have very strange tongues that they use to quickly whip out ants from their nests. Their tongues developed over a long period, and are quite unique when compared to other closely related species, such as armadillos and sloths.

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Male mammals and nipples -

So why do male mammals have nipples when only females need them? Males and females develop along very similar lines using much the same genetic recipe. Characteristics of one sex will, then, be expressed in the other as long as they don't cause any disadvantage. Male nipples neither help nor hinder.

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Green anole lizards adapted to an invasive species -

When brown anole lizards invaded green anole territory in Florida, the green lizards adapted in just 15 years. The green lizards developed larger toe pads and more scales, which helped them cling to higher branches to avoid competition from the brown lizards on lower branches.

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Owls adapted to warmer winters -

A 2011 study revealed that while temperatures rise and there's less snow in Finland, more tawny owls are brown instead of their natural gray. As winters are becoming milder, natural selection is favoring feathers that camouflage with the brown forest instead of snow.

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Dogs of the world -

There is clear evidence that dogs were derived from gray wolves during the initial phases of domestication. Today there are over 340 breeds of dogs. 

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Pollution resulted in the color change of moths -

The peppered moth was once light in color. But it adapted rapidly to the pollution brought on by the Industrial Revolution. The moths mutated to become much darker, allowing them to camouflage against predators. 

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Some birds lost the ability to fly -

Many modern flightless birds, such as penguins, ostriches, and emus have ancestors that were able to fly. Their flightless adaptation evolved due to different environmental changes.

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Moles and their large paws -

Moles spend their lives digging tunnels so their massive, clawed front paws are built for excavation. Evolution has even transformed one of their wrist bones into an extra thumb to help them shift soil in bulk.

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How pandas grip their bamboo -

Moles aren't the only mammals to have a false thumb from a wrist bone. A similar structure helps giant pandas grip bamboo. 

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The rattlesnake's rattle -

So how does a rattlesnake's rattle work? Well as it grows, a rattlesnake accumulates small hollow segments of each shed skin at the tip of its tail, which clank together menacingly when shaken. The result is their alarm signal to warn potential aggressors to back off, or to distract prey. 

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Many species are the result of human choice -

Many of the pets, farm animals, and garden flowers we see today are the result of human choice. For example, farmers chose to breed chickens that laid the best eggs. 

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Bedbugs adapted to pesticides -

Bedbugs were common in the 1940s and '50, but when humans introduced insecticides to control the critters, the plan totally backfired. By the '60s future generations of the bugs were equipped with thicker shells, more resilient nerve cells, and an enzyme that helps break down toxic substances. Yikes.

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Giraffe necks evolved to a higher state of being -

Their elongated necks help giraffes reach the highest food sources. Also, males now use their long neck as a way to demonstrate their strength and fitness to females. 

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Dragonflies existed before dinosaurs -

Dragonflies were the first creatures to take to the Earth's skies around 406 million years ago. Back then, though, they were massive! 

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Salmon adapted to human interference -

When commercial fishing in the '20s threatened Chinook salmon from Alaska to California, the fish became smaller and shorter-lived. Later, pink salmon adapted their migration habits, swimming earlier due to climate change. Today, salmon are migrating from the ocean to rivers two weeks earlier than they did 40 years ago, in direct response to warmer ocean temperatures.

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Potato-eating insect became resistant to insecticides -

The Colorado potato beetle is another insect that became resistant to human-made insecticides due to a mutation. Now they can consume potato crops coated with insecticide.

Sources: (Discover Wildlife) (Wildlife Informer) (Mental Floss) 

See also: Fascinating ways animals communicate

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