What Are Humans? Animals, Mammals, or Neither?

by Dr. Elizabeth Mitchell on August 28, 2019

Are you an animal? Are you a mammal? People eager to use words correctly want to know!

Are you an animal? If a man eats with deplorable table manners, his wife might ask him if he had been raised in a barn. If the guy down the street behaves wildly, you might call him an animal, though not to his face. If you hear on the news of a couple like Bonnie and Clyde going on a murder spree, you might remark that they are behaving like animals.

The very fact that we might derisively call someone an animal based on “animal-like” behavior illustrates the fact that we humans generally consider ourselves different from animals.

What is it about these behaviors that prompts us to call a fellow human an animal, whether in jest or seriously? It is any behavior that we deem less than civilized, behavior that we associate with animals more than with humans. But do those behaviors mean those individuals are actually animals? Of course not. The very fact that we might derisively call someone an animal based on “animal-like” behavior illustrates the fact that we humans generally consider ourselves different from animals.

Another indication of the general understanding that humans and animals are fundamentally different is found in our dietary choices. Your non-vegetarian neighbors eat animals, and this probably does not bother you. But if your neighbors included humans on their meaty menu, you would hesitate to go outside and you certainly would not attend their barbecue.

And what about the testing of new medicines? Thanks to ethical concerns for the welfare of animals, you might not be too happy about the latest drugs being tested first on animals, and you would doubtless demand any testing be conducted in a humane fashion, but you’d be a lot more unhappy to think they were initially tested on humans. Ethical concerns about the treatment of animals and moral aversion to cannibalism both reflect the common assumption that humans are not animals. Humans are in a special category all to themselves.

Context and Worldview

In ordinary, non-scientific conversation, the word animal excludes humans. In fact, if you hear someone consistently lumping humans in with animals in a non-scientific context, you probably have a clue about his or her worldview. People with an evolutionary worldview believe that all multicellular organisms evolved from single-celled organisms, with animals, plants, protists (such as multicellular algae), and fungi comprising the main lines of descent. Thus in an evolutionary worldview, humans are just highly evolved animals. Humans are not fundamentally different from animals according to an evolutionary worldview.

As the direct descendants of the two people God made, we too are made in God’s image.

On the other hand, humans are fundamentally different from animals due to our unique origins, according to a biblical worldview. A person with a biblical worldview understands that God created the first humans in his image distinct from animals. As the direct descendants of the two people God made, we too are made in God’s image. Humans, not animals, are, in Genesis 1:26, given dominion over the earth, and that includes the animals. Thanks to this distinction, humans are accountable for moral choices in a way that does not apply to animals. And humans have the unique capacity to communicate with God, our Creator. Despite our sins, we may be restored to fellowship with God through the shed blood of God’s Son Jesus Christ, who is fully God and fully man.

Twenty Questions

The game twenty questions typically opens by indicating whether the secret word is “animal, vegetable (or plant), or mineral.” For instance, a wooden table and chair would be “vegetable” because they were made from a plant—wood from a tree. A silver spoon or a painted rock would be “mineral.” And a chimpanzee or a puppy would be “animal.” So would your grandmother. But you’d probably feel uncomfortable referring to your grandmother as “animal” for the reasons we’ve outlined above. Such a categorization would be insulting. Nevertheless, placing all that surrounds us into proper categories based on similarities is not just something we do in the game of twenty questions. It is also something we routinely do in science.

Biology is the study of living organisms. Many organisms are single-celled. Multicellular organisms belong to one of four groups, or kingdoms—Animalia, Plantae, Protista, or Fungi. Just exactly how many kingdoms living things should be divided into has varied a good bit over the years. Most of these changes have been based on the way single-celled organisms are classified, and usually on the basis of the increasing knowledge available about them as technology has advanced. Nevertheless, biological classification—or taxonomy—has historically been mostly based on shared observable characteristics.

What It Is, Or Where It Presumably Came From?

In an effort to fine-tune biological classifications, there has been a modern trend toward considering the evolutionary origins of living things when categorizing them. Classification according to observable characteristics is called Linnaean taxonomy, because in the 18th century Carolus Linnaeus developed this practical classification system based on the similarities and differences among living things. However, since the mid-20th century presumed phylogenetic considerations about the evolutionary relationships of living things over the unobservable millions of years has become increasingly popular, especially since the advent of technology to allow detailed comparison of DNA.

For example, the evolutionary claim that birds are the evolutionary descendants of dinosaurs has led to the notion that birds are dinosaurs. This “phylogenetic” line of thinking therefore sees birds as reptiles. Some authorities now also technically consider mammals to be reptiles too, though not dinosaurs. Both birds and mammals are believed by evolutionists to be distant descendants of the original reptile, with the mammalian branch and the dinosaur-bird branches separated by millions of years of evolutionary divergence. Is it possible to know that these evolutionary relationships are true? Did any scientist observe these alleged evolutionary divergences? No. These claims are based on anatomical and genetic comparisons of living creatures as well as the observable characteristics of fossils viewed through evolutionary assumptions.

What Is an Animal, Anyway?

Scientifically speaking, what is an animal?

So, scientifically speaking, what is an animal? Animals are multicellular organisms that must consume organic matter and breathe oxygen to stay alive and are generally able to move. Animals are also generally able to reproduce sexually, through the combination of gametes (egg and sperm) to form a zygote. An animal zygote then develops into a hollow ball of cells before going on to develop into a more mature form. Humans and hamsters both fall into this “animal” category, whereas apple trees and mushrooms do not. Based on observable biological characteristics only, then, without dependence on evolutionary assumptions, humans could technically be considered animals.

Yet humans do differ from animals. Recognition of this fact, even in the biological sciences, is acknowledged in the fact that zoology is the study of non-human animals. And despite the many anatomical and genetic characteristics we share with animals—footprints of the wisdom of our common designer, the Creator God—humans possess many anatomical traits, substantial genetic differences, and unique behaviors and abilities that no animal exhibits.

So, are humans animals by definition? The answer depends on the context of the question. If the question is purely a biological one in which all living things must be classified in the appropriate category, then the answer would be “yes” simply because the kingdom Animalia is the only one open to us. This is the case even apart from any evolutionary claims, as humans share all the necessary observable characteristics required for inclusion in the animal kingdom. Linnaeus, operating from a biblical worldview, placed humans—dubbed Homo sapiens—in the kingdom Animalia. Of course, evolutionary thinkers see humans as merely highly evolved animals based on their presumptions about the origins of all living things. In any other non-evolutionary context, however, the answer is “no”; humans are distinct from animals.

Are We Mammals?

If humans are not really animals, except in the purest biological sense, then why do we classify humans as mammals? The answer is again one of context. The word animal is routinely used in non-biological ways in ordinary conversation, and in those contexts humans are distinctly different from animals. However, the word mammal automatically carries scientific implications.

Remember that classification system business in which all living things must belong to a particular kingdom, with four kingdoms in the current taxonomic system containing multicellular organisms. Well, the modern version of the Linnaean classification system that includes all animals in the kingdom Animalia has a number of subcategories also based on observable shared characteristics. Those subcategories include phylum, class, order, family, genus, and species. One of the classes in the Animalia kingdom is Mammalia.

Mammals are member of the Mammalia class. What characteristics do mammals share? The list has been refined since Linnaeus gave us his in the 18th century. Mammals are warm-blooded and breathe air. They have mammary glands with which females can feed their young. Mammals, including whales, possess some sort of hair or fur at some time in their lives, however sparse it might be. In addition, mammalian brains include a neocortex in which many higher order brain functions take place. Mammals have three bones in the middle ear and a lower jaw consisting of a single bone. Mammalian teeth are replaced no more than once over a lifetime. Mammalian hearts are all four-chambered, and mammals all have diaphragms to aid their breathing. By these criteria, humans would qualify as mammals.

Extinct Mammals

When it comes to classifying fossils of extinct animals, the presence of tissues observable only in living creatures, such as mammary glands, must be overlooked in favor of characteristics that can survive the fossilization process. Some of these characteristics are seen in all living mammals. These include, for example, a characteristic jaw joint attaching the single-boned lower jaw to the skull. Another example is the presence of two knobby bones at the base of the skull where the head articulates with the vertebral bones. If soft tissues and evidence of skin appendages like fur have been destroyed, only such traits as these can offer clues as to whether an animal was a mammal or not. Fossils certainly cannot nurse their young! Yet so often we see a news article reporting the discovery of a mammalian ancestor millions of years old.

Not surprisingly, as with other categories in biology, the modern tendency to include presumed evolutionary relationships in the classification scheme has led to some modifications. Furthermore, many evolutionary assumptions color the classification of fossils, as the fossil record is viewed by evolutionists as the fragmented record of evolutionary relationships over millions of years. And fossils themselves are often fragmented. Thus, in determining whether or not a particular fossil is mammalian or not typically involved not only the study of its observable characteristics but also assumptions about traits that are not in evidence and how those heritable traits may have changed over great spans of time. Such assumptions, within an evolutionary worldview, could suggest that reptiles diverged to produce the first mammal from which all mammals eventually evolved. Given that observational science has never demonstrated any way in which one kind of creature can obtain the genetic information to change into a new, completely different kind of creature, we must ignore the claims about mammalian evolutionary origins when considering how humans fit into the world of mammals.

Whether or not a fossil is identified as “human” often depends on a checklist of characteristics.

Fossilized bones that appear to have belonged to either an ape or human offer a particular challenge. You might think that it would be easy to tell whether old bones belonged to a person or an animal, but it can be tricky. Humans do share some characteristics with primate animals, so a partial skeleton or just a few isolated bones might not contain the necessary bits to make identification clear. This is especially a problem if you recall that there are some extinct varieties of humans, such as Neanderthals, who have some skeletal differences when compared with modern humans. Paleontologists trying to identify fossils can make mistakes as they examine bones possessing the common designs we humans share with many animals. Whether or not a fossil is identified as “human” often depends on a checklist of characteristics. This could leave someone thinking a human is nothing more than a sum of the appropriate parts, especially if the paleontologist has an evolutionary worldview that views humans as just highly evolved animals that have acquired the necessary parts to cross the line into humanity.

Are We Mammals?

So, are humans mammals? Yes. This question is one of scientific classification. And no matter what classification scheme one adheres to, humans fall into the mammalian category. Classifying humans as mammals—or biologically even as “mammalian animals”—should in no way imply belief that humans are the products of evolution. A mammalian classification is merely an acknowledgement of the many design features we share with many of the animals God created.

Though we are mammals, humans are nothing less than the amazing beings God created a little lower than the angels (Psalm 8:4-5). Just as Linnaeus included humans in the Animal Kingdom, so we modern Bible believers can consider humans to be— in the scientific and biological contexts—both animals and mammals. Yet we are so much more. God created humans in his own image, distinct and separate from any other living thing he created. And our Creator God is so mindful of us that He sent Jesus Christ into the world as a human to take the penalty for our sin on himself so that we may have eternal life with him in heaven.


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