Deep Ancestry: Our Story

Anyone who is interested in family history, or anyone who has ever gone to a library or archive to undertake genealogical research knows that while the subject is an exciting one, the work can be tedious and the resulting picture often fuzzy.

This is where we stand with regards to family research writ large, that of modern humanity. To be sure, we have come a long way since we humans even became aware of the fact that we had a very long history, or a deep ancestry. Consider the day, now more than 180 years ago, when people went into a cave in Belgium and encountered remains later identified as belonging to a Neanderthal individual. Compare that against our current understanding of human evolution. How we got here is an interesting story and it is an interesting tale to relate,. Where we go from here is equally intriguing.

Here is part one: how did we get here?

Traditionally, we rely on three main sources of information when studying human origins, our origins. These sources are: the material remains of that past (including both fossil remains and man-made tools), genetics and comparative primatology. The latter refers to observation of current non-human primates and possible correlations between their habitat and behavior with the environment in which our ancestors once lived and their behavior. If there is one constant in the picture generated by these sources is that it is always being refined and updated. Such is the nature of scientific endeavor: it never stands still. Thankfully, our thirst for greater understanding is never slaked either. There is always more to investigate.

Material remains have been the backbone of paleoanthropological studies. After all, what could be a better illustration of human evolution than a fossil of an ancient ancestor, or a tool made by a distant relative of ours? By carefully plotting where these remains have been found, we can reconstruct a picture of human evolution, we can start to see where our earliest ancestors once arose, evolved and eventually migrated from. By studying their tools, we can see human inventiveness at work. At first this is a tediously slow process, but eventually we see it picking up pace to the point we are today: new gadgets developed on a daily basis.

For a while, as people were studying fossil human remains, others were investigating genetics. However, initially the practitioners of these two pursuits did not know of each other’s work, or, did not realize how their work could benefit from the other person’s insights. And so we see how Mendel and Darwin were contemporaries, but their respective scientific insights and breakthroughs did not cross over and inspire the other.

DNA rendering
Creative Commons License photo credit: ynse

Our genetic makeup is the result of millions of years of evolution.

Since the Human Genome Project was completed in 2003, we have learned a lot about our genetic makeup. Since then, the chimp genome, gorilla genome, and the orangutan genome have been finished; by the way, the latter was sequenced in our own backyard here in Houston. This provides a nice platform to start comparing our genetic makeup with that of our close primate relatives, and find out where we differ, and, more interestingly, how similar we are below the surface. It turns out we are quite similar.

The difference 1% makes.

Differences, no matter how ostensibly small, remain important. One can be in awe about the fact that we share around 99% of genes with chimps. One could also turn that around and say “See how much difference 1% makes?” That difference, in turn, may help us figure out when in time we started to go our own way, after the split from a common ancestor. This is where the notion of a molecular clock comes in. This concept has been used to “to investigate several important issues, including the origin of modern humans, the date of the human/chimpanzee divergence, and the date of the Cambrian explosion.”

Thus we see in the literature that orangutans, with whom we share around 97 % of our DNA, split from the family tree around 16 to 15 million years ago. Humans and chimps became their own branches on the family tree around 6 to 5 million years ago.

As one researcher recently put it: “There remain signals of the distant past in DNA, and our approach is to use such signals to study the genetics of our ancestors.”

The concept of the molecular clock continues to be refined as our understanding of its potential and limitations has grown. For better or worse, however, it provides us with a tool to help situate major branching events on the family tree. This brings us to our own immediate past, our place in history, when modern humans appeared on the scene.

Modern Humans

Discoveries made in East Africa date the emergence of modern human beings to about 200,000 years ago. Two skulls, found in 1967 in Ethiopia were recently identified as the earliest known modern humans. While that makes all of us Africans, it data from mitochondrial DNA have suggested that our ancestors did not make it out of Africa until 60,000 years ago. The archaeological record seems to disagree, however. Man-made tools twice that age have recently been found in the Arabian Peninsula.

It is at times like these, when dates provided by genetics and archaeology diverge, that we hear voices criticizing the invalidity of this approach. What we will see happen, however, is that this apparent disjunction between two sets of data, will spur on researchers to find where the source of this disparity lies and resolve it. Were that to be impossible then we would have to go back to the drawing board and rethink our ideas about human evolution and the timing of critical events related to it.

Now for part two: where do we go from here?

As people become more mobile, we are now finding our mates much further away than we did just a few generations ago. This means that it will become more difficult to check that box on the census form asking for our ethnicity. It also means that we are slowly becoming more homogenized. Indigenous cultures are disappearing and language follow suit.

To get an idea of how exhilarating and mind-boggling this pursuit of science can be, I would like to invite the reader to attend an upcoming lecture.

On March 7, the Houston Museum of Natural Science will host Dr. Spencer Wells, lead scientist of the Genographic Project.

His lecture, entitled “Deep Ancestry: Inside the Genomic Project,” is brought to us by the Leakey Foundation. Dr. Wells is an Explorer-in-Residence at the National Geographic Society and Frank H. T. Rhodes Class of 1956 Professor at Cornell University. Dr. Wells will share with us how the Genographic Project, using data from hundreds of thousands of people, including members of the general public, the Genographic Project is deciphering the migratory routes followed by early humans as they populated the Earth.

I look forward to this lecture, and hope to see many of you at the museum that evening.

In the meantime, a pop quiz.

Q: What do the following individuals have in common?

Brazilian indian chiefs, Kaiapos tribe, during a collective interview.
Left to right: Raony (state of Mato Grosso), Kaye, Kadjor, Panara (Pará)
Creative Commons License photo credit: Valter Campanato, Agência Brasil (ABr). April 17, 2005
Ethiopian Orthodox Christian woman – Lalibela, Ethiopia
Creative Commons License photo credit: Dirk Van Tuerenhout
Lake Titicaca – Uros people
Creative Commons License photo credit: Dirk Van Tuerenhout

A: They are us. We are them. This is us.

Human evolution: the year 2010 in review (Part 1)

That’s some good-looking gombo, cher!

gumbo
Creative Commons License photo credit: Southern Foodways Alliance

This blog contribution aims to be like a good Louisiana seafood gumbo: thick, hearty, spicy, and made up all kinds of finger-licking ingredients (pun intended). There will be some French, which would be apropos, some Latin as well, and all kinds of discoveries related to human origins, as they transpired this past year. I will follow up with a second part in a week or two with an observation and a comment.

In an earlier blog, “A pinky’s promise,” I wrote about the incredible discovery that was made early in 2010 when DNA analysis was performed on one small finger bone retrieved from a cave in Southern Siberia. The bone dated to a period (50,000 to 30,000 years ago) when all scientists assumed that the only living humans were either Homo sapiens sapiens or Neanderthals (perhaps we should now be saying Homo sapiens neanderthalensis, but I am getting ahead of the game). This first assumption proved to be wrong.

Entrance to the Denisova Cave
Creative Commons License photo credit:ЧуваевНиколай

In 2008, DNA analysis carried out on a single finger bone revealed that there was a third species of human walking the earth at that time. Toward the end of 2010, this view was corroborated by additional DNA analysis of a few teeth that were found in the same Denisova cave. The Max Planck Institute in Leipzig announced that these so-called “Denisovans” represent a new species.
More interesting still, some of their DNA is still around: the “Denisovans” interbred with the ancestors of Melanesians. This implies that at one point, this third species was quite widespread in Asia. If these conclusions hold up, the lesson we should take away from this breakthrough is that every little scrap of evidence counts when studying human origins, even a single tooth, or a finger bone. I wonder how many single finger bones or teeth have been overlooked in the past, or are still awaiting re-discovery in a museum drawer somewhere.

Neanderthals were also in the news this past year. For years, researchers have been vexed by questions such as “Who were these people?”, “Where did they come from?”, “What made them extinct?” and last but not least “Is there a little bit of Neanderthal in (some of) us?”

With regard to the last question, also discussed in earlier blogs, the way in which we answer that question will result in a different scientific (read: Latin) nomenclature for Neanderthal. Allow for the possibility of interbreeding between Homo sapiens and Neanderthals and also agree that their offspring was fertile, i.e., they successfully reproduced, then you would have to refer to Neanderthals as Homo sapiens neanderthalensis. If you disagree with this idea, and think it was unlikely these two populations interbred, or that their offspring was not capable of producing fertile offspring, then you would have to refer to Neanderthals as Homo neanderthalensis. This classifies them as a species separate from modern humans; by definition, species cannot interbreed and produce fertile offspring.

Man
A Happy Neanderthal
Creative Commons License photo credit: erix!

The latter way of thinking was long popular among paleoanthropologists. Now the pendulum is swinging the other way. Scientists at the institute decoded the Neanderthal genome and compared it with that of modern humans. The result? In their words: “By comparing that genome with those of various present day humans, the team concluded that about 1 percent to 4 percent of the genome of non-Africans today is derived from Neanderthals.”  In people speak: up to 4% of a European’s genetic makeup could be inherited from the Neanderthal lineage, now extinct.

Before you check for hair on your knuckles, thank (or blame) a single finger bone and a few teeth, as well as the staff at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany for all this.

Lest we all (well, at least those of us of European descent) break out in hives and run for the nearest hills, scientists were quick to add: “[T]he Neanderthal DNA does not seem to have played a great role in human evolution.”

Certainly, 1 to 4% overlap in genetic makeup is not very much, but it is a whole lot more than we were willing to consider just a year ago. Differences between Homo sapiens sapiens and Homo sapiens neanderthalensis remain significant. The overall physical appearance of a modern human is very different from that of a Neanderthal. In terms of behavior, and cognitive abilities, the two subspecies also appear to be a world apart, never mind they shared portions of our planet.

Comparing Neanderthals and modern humans
One of the areas in which there were both similarities and differences was diet. These insights also came out this past year.  Did you know that Neanderthals ate their veggies? And that they liked to cook them as well? Perhaps you did. However, did you also know that they were not averse from eating each other?

Check back next week to see more on this, when Dirk discusses teeth, DNA, and his own conclusions to 2010 in review.

Flickr Photo of the Month: Trappings of Yingpan Man [Dec. 2010]

Trappings of Yingpan Man. 3rd - 4th century
Trappings of Yingpan Man. 3rd – 4th century by cybertoad, on Flickr.
Posted here with permission.

There are some amazing photographers that wander the halls of HMNS, and when we’re lucky, they share what they capture in our HMNS Flickr pool. This month, we’re re-starting a series where we’ll share one of these photos on the blog each month.

Elaine (cybertoad on Flickr) took this photo during a Flickr meetup in our current Secrets of the Silk Road exhibition. From the photographer:

The Beauty of Xioahe may have been the exhibit’s celebrity but the Yingpan Man still captured me. His simple funerary mask with the delicately painted eyebrows and the gold leaf evoke a sense of elegance and peace that I hope he carried with him into the after life.

Inspired? Most of the Museum’s galleries are open for photography, and we’d love for you to share your shots with us on Flickr, Facebook or Twitter. Check out the HMNS photo policy for guidelines.

Photography is prohibited in this exhibition during general hours. If you’d like to join one of our Flickr meetups, check out our Flickr group Discussions page for updates on upcoming events.

Want to see Yingpan Man for yourself? Secrets of the Silk Road is only on display for a few more weeks!

Of Chinese mummies, and a relative of a famous German WWI fighter pilot

While I was reading up on the archaeology of the Tarim Basin for our new exhibit, Secrets of the Silk Road, I kept thinking of “the artist formerly known as Prince.” Why? What in the world does he have to do with 4000-year old mummies? The answer is simple. There is one aspect he and the Xinjiang sites have in common: they have an awful lot of names. Over the years, sites have been named in various languages, English, Chinese and Uyghur; occasionally they have also been named after individuals. Anyone interested in this subject matter may at first be very confused by these multiple names.

 Sven Hendin

Let me start out, however, with a much simpler explanation about the origin of the expression Silk Road. The term Silk Road is the English translation of the German “Seidenstrasse,” a term coined in 1877 by Freiherr Ferdinand von Richthofen. This German geologist and uncle of famous World War I fighter ace, Manfred von Richthofen, chose silk to symbolize the trade items that made it from China to the Mediterranean and this term has been used ever since. Ferdinand von Richthofen’s legacy extends beyond contributing the terms Silk Road; one of his students was a Swede named Sven Hedin. Sven became a very accomplished student of the Tarim Basin history, as we shall see below.

Scientists have been able to collect and study to some degree about 500 mummies (Mallory and Mair 2000, pp. 179 – 180). We know that the remains of thousands of people were buried in the desert in the course of several millennia before the arrival of the Han Chinese in the region. Some of these individuals remain at rest, others have been found by looters and their tombs were ransacked in a futile attempt to find treasure.

The mummies have been found in various cemeteries in the Tarim Basin. In the next paragraphs, I will review some of these burial places, concentrating on those where mummies with Caucasian features have been found.

One of the two mummies currently on display at the museum is known as the “Beauty of Xiaohe,” named after the Xiaohe cemetery. The Xiaohe cemetery goes by several names. In 1934, Swedish archaeologist Folke Bergman reached a site in the Lop Nor area; this settlement contained a cemetery on a hill marked by wooden posts. (An example of this burial arrangement is on display at the museum as well.) The site was close to a river bed, which Bergman named Xiaohe, or “Small River.” The cemetery itself got several monikers, starting with “Ördek’s necropolis,” after a Uyhgur guide by that name who had discovered the site in the 1910s, while working for the above mentioned researcher, Sven Hedin. Researchers established that the settlement and the associated cemetery belonged to the Gumugou culture, also known as the Qäwrighul culture. Another “beauty” found in the region, a mummy known as the “Beauty of Loulan,” also belonged to this culture (Romgard, 2008, p. 13).

After its initial discovery, the Xiaohe site drifted back into anonymity. It was rediscovered in 2000. A Chinese translation of Bergman’s book (Bergman, 1939) became available in 1997. It brought the site to the attention of Chinese scientists, who were able to re-discover the site (Romgard, 2008, p. 20, n. 38).

 Hedin with Folke Bergman on Hedin’s final expedition, 1934
© The Sven Hedin Foundation

The Xiaohe cemetery contains the largest number of mummies ever found at a single site (Romgard, 2008, p. 20). A total of 167 tombs were excavated, many of them containing mummies with clear European features. The earliest graves date back to ca. 2000 BC (Romgard, 2008, p. 21). The presence of woolen garments is a good indicator of very early links between West and East, as sheep did not exist in early China (Romgard 2008, pp. 21-22).

Northeast of Lop Nor, near the oasis town of Hami, archaeologists encountered a small number of mummies of Caucasian origin at the Yanbulaq cemetery. Eight out of a total of 29 examined human remains were identified as such (Romgard 2008, p. 22). This cemetery, dated back to the Bronze Age as well, contains further proof of western cultural traits moving from west to east. The presence of people of Caucasian extraction, as well as woolen knit-ware and mud brick architecture spread eastward to the Tarim Basin and then China (Romgard 2008, p. 22).

Qäwrighul Cemetery, located close to Bosten Lake in the Tianshan Mountains, is part of the Chawuhu culture (Romgard, 2008, pp. 15- 16, 23-24). It dates to 1000 – 400 BC. Human remains encountered here display a mix of Caucasian and Mongoloid features. The people who were buried here lived in an area that served as a passageway between the eastern parts of the Tarim Basin and parts further northwest. Similarities in material culture between this culture and areas in Siberia and Kazakhstan imply that migrations occurred in this part well before the official opening of the Silk Road (Romgard, 2008, p. 24).

The idea that some of the basic building stones of civilization came from the west into China did not receive a universal welcome among Chinese scholars. As late as December 1999, Chinese scholars argued that the reverse had happened, that prehistoric cultures from China had gradually advanced to the West (Romgard 2008, pp. 29 – 30). However, the pendulum is now swinging in the opposite direction, and acceptance of western influences on the genesis of Chinese culture is growing (Romgard 2008, pp. 30-32).

Scientists now feel confident enough to state that “the idea of a European entry either directly from the West or from the steppe cultures in the north is [today] the prevailing theory (Romgard 2008, p. 33).

In the course of more than a century, explorers have mapped sites in the Tarim Basin; they published their findings and then there was a long hiatus. Both World Wars impeded research, and the civil war in China following WWII made any scientific efforts in that part of the world impossible to pursue. It was only after China opened to the West, and travel to the Tarim Basin  became easier, that progress was made once again. The translation of research journals from European languages into Chinese rekindled that effort as well. One wonders what the next century will bring.

Sources:

Bergman, Folke, 1939. Archaeological researches in Siankang. (Reports from the Scientific Expedition to the North-Western Provinces of China under the Leadership of Dr. Sven Hedin. The Sino-Swedish Expedition. Publication No. 7), Bokförlags Aktiebolaget Thule – Stockholm.

Mallory, J.P. and Victor H. Mair, 2000
The Tarim Mummies. Ancient China and the Mystery of the Earliest Peoples from the West. Thames and Hudson, London.

Romgard, Jan, 2008. Questions of Ancient Human Settlements in Xinjiang and the Early Silk Road Trade, with an Overview of the Silk Road Research Institutions and Scholars in Beijing, Gansu, and Xinjiang. Sino-Platonic Papers, Nr. 185.