Monkey business

 When asked their opinion about human evolution, some people will answer: “I cannot accept that we came from monkeys.”

We should all agree with that sentiment. Humans are no monkeys. But we are part of the Primate Order.

In an earlier blog  I wrote about Carl von Linné to  and his way of classifying plants and animals using observable traits.

Under the Linnaean system, human beings belong to the Primate Order. Within this Order, there are two sub-units, referred to as suborders: the Prosimians and the Anthropoids.

Fans of the movie Madagascar ought to be very familiar with Prosimians, a family that includes lemurs and lorises.

Anthropoids include New World monkeys (such as marmosets, tamarins, capuchin monkeys, howler  and spider monkeys) as well as Old World monkeys, apes and humans (such as baboons, colobuses, gibbons, siamangs, orangutans, gorillas, chimpanzees, bonobos and humans).

All of the animals just mentioned are still with us. Each one of these is subject to evolutionary pressures and some (like us humans) are flourishing and others (like chimps and gorillas) face ever-diminishing natural habitats.

But this all relates to the present. How does it apply to the past?

Together with gibbons, siamangs, orangutans, gorillas, chimpanzees and bonobos, humans are members of the Superfamily of Hominoidea (a.k.a. apes and humans). The classification of humans and apes into this Superfamily reflects a common ancestor in a distant past.

Moreover, recent DNA studies comparing human genetic information with that of other non-human primates has shown a high degree of genetic similarity. For example, DNA from a modern human is close to 99% identical to that of contemporary chimpanzees. This further supports descent from a common ancestor.

Next time you hear a remark about humans evolving from monkeys, you can set the record straight: one species did not come from the other. Humans and apes simply share a common ancestor.

No monkey business required.


What kingdom are you from?

We’ve seen how Carl Linnaeus’s system classifies Lucy. How is the classification that refers to her different from the one that refers to us?

Applied to humans, a Linnaean chart could be filled out in the following way. (Notice the prevalence of Greek and Latin terminology.)

Domain: Eukaryota – containing all organisms which have cells with a nucleus.

Kingdom: Animalia – including organisms with eukaryotic cells that have a cell membrane but lack a cell wall, are multicellular, and heterotrophic (meaning that they cannot synthesize their own food, as plants do.)

Phylum: Chordata – including animals with a notochord, dorsal nerve cord, and pharyngeal gill slits.

Subphylum: Vertebrata – animals possessing a backbone, which may be made of cartilage, to protect the dorsal nerve cord.

Class: Mammaliaendothermic vertebrates with hair and mammary glands which, in females, secrete milk to nourish the young.

Subclass: Placentalia – including animals that give birth to live young after a full, internal gestation period.

Order: Primates – including animals with a collar bone, eyes that face forward, grasping hands with fingers, and two types of teeth: incisors and molars. 

Family: Hominidae – including primates with upright posture, a large brain, stereoscopic vision, a flat face, and hands and feet with different specializations (such as grasping and walking).

Genus: Homo – having an s-curved spine, “man.”

Species: Homo sapiens – characterized by a high forehead, well-developed chin, and thin skull bones.

While Latin and Greek are no longer used when scientists write or e-mail each other, these languages continue to survive in the names given to plants and animals. For those few among us who did study Latin and Greek, here is one practical application of hours and hours of learning vocabulary and conjugating verbs: it allows one to more easily see the origins of the terms used and thus facilitates our understanding of what is meant.

For all those others who did not study these ancient languages, consider the old saying “The more it changes…”

It’s all Greek to me

The world of science is full of terminology borrowed from dead languages such as Ancient Greek and Latin. This is the natural result of the fact that in the 17th and 18th century scientists tended to use Latin to communicate with each other.

While this tradition has now changed in favor of languages that are still very much alive, the legacy continues in the terms we use to classify plants and animals.

When we refer to modern humans, we call ourselves Homo sapiens sapiens, or the Latin expression for “Human, smart, smart.”

We owe this expression and many others to Carl von Linné,or, as he was known to his colleagues, “Linnaeus.”

This Swedish scientist, who lived in the 18th century, set out to classify and label plant and animal forms based on observable similarities in shape. Reflecting the thinking of his time, Linnaeus wanted to reveal the order that existed in God’s creation. His research resulted in a number of classificatory units that are still used today:

Domain
Kingdom
Phylum
Subphylum
Class
Subclass
Order
Family
Genus
Species
Subspecies

Linnaeus also initiated the custom of using two terms (a binomial) to refer to individual life forms.

Each of these binomials, such as Homo sapiens, is very specific and cannot be applied to anything but to members of that genus and species. Similarly, an Australopithecus afarensis refers to Lucy’s kind and nobody else.

The final product of evolution

Here is another sobering thought: we are not the final product of evolution. As a species that exists, reproduces and mutates, we too are subject to change over time.

So, what can we learn from this week’s discussion (here and here)? I would say several things:

First of all, Lucy and her kind have proven to be much more resilient than us, at least so far.
As a modern human species, we continue to evolve. Our children and our children’s children will continue to exhibit mutations that make them unique.
If enough time passes, this has the potential to change us as a species and it makes all of us participants in this never-ending process called evolution.
I’ll leave you with a question I like to pose to our visitors:

Do you think we will be able to survive another 400,000 years as a species, in order to be as successful as Lucy and her fellow Australopithecines?