If humans came from monkeys, then why are monkeys still around?

This is a question that one frequently encounters on various blogs. It expresses a desire to learn more about one’s origins, but reflects a misunderstanding of how science currently interprets these origins.

The question has the potential to confuse, but the answer is very simple: monkeys, apes and humans evolved from a common ancestor.

We are the only representative of the human lineage still around; the fossil record is replete with earlier hominids that did not survive. The same applies to the non-human portion of the Primate Order: some of them are around today, many more have become extinct.

So what is this business with a “common ancestor?” This expression refers to earlier forms we can trace our origins back to. Consider this image:

Starting at the bottom of the image, there are lines extending upwards, towards a number of branches, such as lemurs, New World monkeys, etc. The intersection of these lineages represents the place where speciation (or the evolution of a new species) occurred.

Let’s take humans and chimpanzees as an example.

At one point, there were no chimps or humans. This is where we place a common ancestor (in this example, we place its existence in the section following the branch leading up to gorillas and before the branching between chimps and humans).

Each of the animals identified is still with us today. As I mentioned in an earlier blog, we are all subject to continuous evolutionary pressures and development. As such, we can say that the monkeys with whom we share our world are not our ancestors, because we live side by side. However, we do share a common ancestor. From this common ancestor, branches lead to us and to other, non-human primates.

Go back to the image one more time. The further down the diagram you go, the further back in time you have traveled. So, looking at the image we can see that monkeys, apes and humans share a common ancestor, but that ancestor existed much earlier than the common ancestor between us and chimps.

Another way to address the question would be to point out that our “family history” is, in fact, “history.” It resides in the past. We cannot find ancestors among current (distant) relatives; we have to go back far in time to find them.

Chimps using tools: Archaeology’s most fascinating discovery of 2007

Chimps using tools: Archaeology’s most fascinating discovery of 2007

In its January/February 2008 issue, Archaeology Magazine listed what it thought were the top 10 discoveries of 2007. Among these was the discovery of tool use by ancient chimpanzees.

A team of researchers led by Dr. Julio Mercader of the University of Calgary in Alberta undertook excavations in the West African nation, Côte d’Ivoire. They encountered a series of hammer stones, some of them dating back 4,300 years, that are thought to have been used by chimps to crack open nuts. Starch residue from several nuts known to be staples in the chimpanzee diet, but not the human diet, suggests that chimps, rather than humans, manufactured these tools.

Dr. Mercader was the first to coin the term “chimpanzee archaeology.”  His discoveries have resulted in the opening of a new research niche within archeology bearing the same name.

In various ways, this particular development is of great importance in the field of human origins. As mentioned in an earlier blog, the capacity of making complex tools is considered uniquely human.

Discoveries like these have prompted humans to add the qualifier “complex” in front of the word “tool.” It is an elegant, yet necessary, way to acknowledge that non-human beings (in this case, chimps are also capable of manufacturing tools, but that until further notice, it is only us humans who use, say, e-mail.

The announcement also showcases how science works: its practitioners are by nature curious creatures. Someone somewhere will inevitably come up with new questions that they will investigate to yield further insights into human behavior. In this case, such insight was achieved by researching non-human primate tool making. For this step forward, we owe Dr. Mercader and his colleagues a debt of gratitude.

A Letter From Lucy: Making no bones about it. (Pun intended)

The other day, I got a visit from Mike. He seemed to be quite an upstanding guy. My kind, really. I had always wondered what would happen to my family. Would they thrive? Would they all be eaten by wild animals before they got a chance to leave Africa? So many questions and no answers. After 3 million years, the wondering can drive you nuts!

And then, I got the chance to travel to North America. Again. This time to see people. I’ve met thousands since arriving, and been amazed at how many different kinds there are – and how happy most seem to see me. Then, there was Mike.

I saw him early in January this year. I’ve been here a while now, so I’ve got the first-impressions thing down. As we exchanged greetings, I passed along my best wishes and a Happy New Millennium from all the folks back home in Ethiopia.

Mike seemed perturbed though. He thanked me for the wishes, but then his eyes kind of glazed over. He seemed not just to see through me, but rather past me. Instead of learning about me, he seemed lost in his own thoughts. As if he did not get who I was and what I represented. I wanted to shout “Mike! It’s me! Lucy. You know, one of your distant ancestors.”

My cries were left unanswered. Mike slowly turned and walked away. “Oh, well,” I thought, “at least he seems to be doing well.” Still bipedal and obviously a much bigger brain. I’m so proud! Uses fancy tools too, it looked like. I never got a chance to use them, and I’m still trying to figure out what most of them are for. We had to survive using our small brains, see. No stone-tipped spears, no burning torches to keep the animals at bay. Definitely no cell phones. Instead we climbed trees at night to stay out of trouble and during the day, as we stood upright – “Just like you, Mike,” I kept thinking – we kept an eye out for predators. Not easy being me, you know. But we all managed somehow.

In fact, I was happy to learn that my kind was around for 600,000 years. Mike, I understand that your people have been around for about 200,000 years. Cool. Keep up the good work. Another 400,000 years and you’ll have been just as successful as we were.

But you left me with a lingering concern for your doubts. I kept thinking “Here I am, Mike. Real bones. Real fossilized remains.” You seemed unimpressed. “Not a replica, and certainly not a fake either,” I wanted to add, but to no avail. You were gone.

Mike, I’ll make no bones about it: thank you for your visit. I was very glad to meet you. But you should use that large brain you’ve got; it’s telling you to look deeper. There is more to me than what you saw.

I am Lucy, and you are my legacy.

PS: Not to hurt your feelings, but I have had dates before, Mike. One guy really fancied me. I think I like him, too.


The Apple Doesn’t Fall Too Far from the Tree

Another approach to figuring out what the very oldest hominids were up to (first discussed in an earlier entry involves observing the behavior of living primates and identifying trends or patterns that have a possible counterpart in the fossil record.

Among some living primates like gorillas and orangutans, there is a marked difference in size between males and females. This marked difference in size between males and females is referred to as sexual dimorphism.

Thanks to the dedicated research of primatologists who spend entire careers observing these animals in the field, we have good data sets related to behavior and how this behavior can be correlated to body size.

For example, male orangutans weigh twice as much as females.

They are much stronger and are prone to violence with other males during mating season as well as with females and their offspring whenever they encounter each other. Long- term observations have established that female orangutans prefer to avoid males outside the mating season.

Sexual dimorphism is also seen in the fossil record. The skeletons of male and female Australopithecines display this feature.

Based on patterns observed today in orangutans and the observed size differences among fossil hominids, we can suggest that behavior observed today may have also existed in the past: Australopithecines males may have acted violently among each other during mating season as well as against females and their offspring whenever they met.

The presence of artifacts, from stone tools to pottery and beyond increases our ability to understand and reconstruct past human behavior. Yet even in those cases where only the fossil record is present and artifacts are totally absent it is still possible to make cautious suggestions as to what these earliest ancestors of ours were up to.