Tanya M Smith

Tanya M Smith

I am a Professor in the Australian Research Centre for Human Evolution at Griffith University. My research helps us to understand ancient human development, behaviour and evolution.

Location http://www.drtanyamsmith.com

Activity

  • You're welcome. I'm about to sign off the course, but will briefly say that the length of time our species is thought to have been around has increased from ~200,000 to ~300,000 years - but the timing of the ancestry of all hominins (including humans) has stayed pretty much the same for the past 15 or so years. Thanks for your engagement!

  • Not silly at all - but difficult to answer without ancient DNA studies. There have been attempts to argue some fossils show evidence of hybridization between humans and Neanderthals - but only one of these has been proven with extraction and sequencing of genetic material - the "gold-standard." I believe that many anatomical features apparent in fossils are...

  • Yes modern humans have smaller teeth and jaws than earlier hominins. This is especially true for the "robust australopithecines" (genus Paranthropus) - which includes Nutcracker Man. This group also has massive expanded premolars - likely of use for crushing and/or grinding hard or gritty foods. And our s-shaped spine allows for our heads to be more passively...

  • @EnidCruickshank Not with physical reconstructions to my knowledge but some fossils have been CT scanned and then refit/reshaped digitally.

  • @AmeliaHare See more on this in the discussion section for "IMPLICATIONS OF THE FINDINGS AT JEBEL IRHOUD"

  • @AmeliaHare It's possible but hard to detect without ancient DNA from the suspected groups. Some of my colleagues favor a kind of 'hybrid model' for humans that does posit genetic contributions from other hominin lineages (known and unknown). The evidence from Neanderthal interbreeding shows a subtle but detectable contribution to all non-Africans. But I don't...

  • @TrishCarter Fair point - but there is a classical set of features (chin, flat face, globular braincase, etc.) and some of these putative early Homo sapiens from Africa don't show all of them clearly. It's possible that these 'classic features' came from different populations - making it hard to know where to set the boundary btw what we'd call a member of our...

  • See my comment above for some clarification.

  • Hi Rob - good question. I'll let you in on a secret buried in fine print in the 2017 paper: Rainer made a miscalculation in his first estimate of the date for the juvenile mandible. When he realized this and corrected it - it was quite consistent with the newer dates. I tease him about it to this day as it would have made our 2007 paper front page news,...

  • Hi Kerry - part of the issue might be semantics - the idea of a biological 'modern human' is classically explained from the lens of a singular 'type specimen' that all others are compared to - allowing an evaluation of whether 'key features' are all present. The Moroccan fossils are part of a new conceptualization of modernity as the product of a coalescence...

  • Hi Sunil - great question. There are classic examples of this (called parallel or convergent evolution) like the wings of birds and bats - which arose independent of each other rather than from a common winged ancestor. This is hard to determine for cultural traditions like tool use. We know some nonhuman primates can do so as well in rudimentary ways, so it's...

  • @DerekHuby I agree that one could misunderstand the idea of a play as leading to an inevitable conclusion biased by the final actor! Evolution isn't directional nor intentional - it's really about the "fit" of species to the conditions of the time. These conditions continue to change - leading to new acts and actors, so to speak. This subject deserves more...

  • Good question. In some instances other partial skulls are used to fill in the missing details, while in other cases some assumptions are made based on other similar species. It can be quite frustrating when you see that these seemingly "neat" skulls were found as dozens or even hundreds of tiny pieces!

  • Hi Brendan - I have colleagues who work on this topic. If you can get access to this journal article through your workplace you might find this to be of interest: https://muse.jhu.edu/article/701861

  • @FionaJohnston @Eleni-PinelopiTsolakidou @MaryAnnAtwood I just uploaded a 20 minute video of an introductory lecture I gave last week on teeth and human evolution that might be of interest to some of you: https://www.youtube.com/watch?v=_Q4lYpcc2Ec

  • @Eleni-PinelopiTsolakidou Hi - welcome to the course! You might enjoy some of the information on my website drtanyamsmith.com (particularly in the News section) or in my popular science book The Tales Teeth Tell. I enjoy chatting to clinicians about this as they don't seem to learn very much about evolution in their training - but are often very curious and...

  • @MaryAnnAtwood Thanks for sharing this video and sparking this conversation!

  • Hello everyone,

    We're delighted that you've decided to join us ~ and hope that we can answer a few of your questions along the way. I've found in my 20 years of work in this field that the story of human evolution continues to change as new fossils are uncovered, new techniques are developed, and new ideas challenge old ones. Our understanding is dynamic ~...

  • Hi folks - a new review of the Denisovans and some current mysteries in interbreeding: https://www.nature.com/articles/d41586-019-00672-2

    Thanks again for taking part in A Question of Time!

    Warmest wishes,
    Tanya

  • Perhaps humans out-competed other hominins too. Hard to prove or disprove, I'm afraid.

  • Yes Ramapithecus is a misidentified hominoid - fossil ape - that shows some basic similarities to hominins. It is much too old (ca. 12-14 mya) to fit with the genetic evidence for the ancestry of our lineage (ca. 6-7 mya). And I've read accounts of up to 30 hominin species depending on whether you prefer to "lump" or "split."

  • Hi Astrid - this is based on a supposition that these fossil were also bipedal in their locomotion - which is in debate in some instances where we don't have full skeletons (not until ~ 4 mya).

  • Thanks @AntjeWilton ~ it's lovely to hear about your interest and I'm glad you're enjoying the course. I'll let you in on a secret too - Rainer made a miscalculation in our 2007 paper on the child's lower jaw (Irhoud 3), and the corrected date is now much closer to the other estimates from this site. But it's true that the past excavations were less...

  • That's part of what makes it so rewarding to be part of this dynamic field!

  • Yes - many muscle attachment sites are larger in male primates, especially when their body sizes are much larger than females (common in species where males can monopolize females, like gorillas). Big silverbacks must spend many hours eating each day.

  • Hi Gina - there is one genus and species called Orrorin tugenensis from Kenya around 6 million years ago. The fossils - aside from the femur (thighbone) - would basically fill a shoe box, and seem to have been assembled from a few different poorly-documented places. However the femur does appear to have been from a bipedal hominin ~ so most of us consider it a...

  • Hi Alan - the line between the australopithecines and the earliest members of Homo was originally drawn by Louis Leakey when he described Homo habilis - "handyman" - which he thought to be the first to make tools and hunt animals. As the other students have shown here - even chimpanzees can do this - so that isn't a good line! Similarly others used to consider...

  • That's right Sandy. Big male gorillas have these ridges too - and massive jaw muscles for spending hours each day munching tough plant matter.

  • Hi Bev - great point - we actually have very little evidence for fossil chimpanzees (just a few teeth). They live in dense tropic forests, which are horrible places for fossil preservation. The fact that the some of the earliest hominins share more in common anatomically with living chimpanzees than living humans is part of the reason we use them as a "model"...

  • Yes these fossil footprints are the very best evidence of bipedalism! Part of the dilemma is how we define a hominin - is it a bipedal ape? Is it a large brained one? Is it a tool-using one? If we go with bipedalism, it is difficult to be sure without nearly complete skeletons, which are quite rare. Paleoanthropologists don't all agree about which of the...

  • Yes I think Neanderthals did produce some kinds of personal ornamentation and there is new evidence for rudimentary cave art made by Neanderthals, but this is often open to different interpretations. However modern humans elevated symbolism to forms of artistic production and technology that are without precedent.

  • Hi Patricia - the last point you make is important - there were several different hominins co-existing at various times and many of them did not leave decedents. We often describe the record as a "tree" or "bush" rather than a linear progression. The Smithsonian website link above shows this nicely.

  • Hi @ChristinaBurdett ~ the story of ancient DNA could easily be it's own course. We don't cover this here but two accessible popular science books on the topic are Neanderthal Man by Svante Paabo and Who We Are and How We Got Here by David Reich - the current leaders in the field of aDNA research and human origins.

  • Hi folks,

    Welcome to A Question of Time! We're looking forward to sharing our research with you and helping you to wade through the constantly-evolving narrative about human evolution. Sometimes it is hard for us "experts" to keep up with all the latest breakthroughs and discoveries - making this field a really dynamic topic of study over the past few...

  • Well the concept of a species is up for debate. Zoologists often use a "biological species concept" as one that includes all individuals who can reproduce and produce viable offspring. As you might imagine, this is impossible to test in fossils. Even in the case of Neanderthals and modern humans the jury is out - it's not clear that both male and female...

  • @ChrisMarcic Well yes there is a subtle effect on the surfaces, but the information inside remains (unless one is a habitual tooth grinder)!

  • Actually there was a mathematical error in the dating done in the 2007 paper on the child's mandible. It's likely to be close in age to the newly dated material.

  • Yes I also study the daily time lines in living and fossil primate teeth, which can tell us so much about age, stress, infant diets, and more. I just wrote a popular science book on this topic: http://www.drtanyamsmith.com/book/

    The work we did on Jebel Irhoud involved using a "super microscope" called a synchrotron ~ here's a related article on how we...

  • Good questions - the origins of speech are heavily debated and not resolved, but some think that by the time complex stone tools appear (such as those made by Neanderthals and early Homo sapiens), hominins must have been communicating as it is rather difficult to produce these without talking. People have tried to reconstruct what Neanderthal speech might have...

  • Hi Cheryl - it turns out that we find ancient hominin teeth more often than any other element, as the enamel crown is nearly "fossilized" when we grow them.

  • Honestly we don't really know the details of how many of the ~30 or so species relate to each other. Things are only really starting to come into focus for species we can recover ancient DNA from, including Neanderthals and the Denisovans. Here's a fairly accurate accounting of recent work on the Denisovans, including evidence that these two "archaic" groups...

  • Hi Stan - there's so much more to the story! I develop this metaphor further in Chapter 5 of my book The Tales Teeth Tell if you want to dive into more specifics (available next month). www.drtanyamsmith.com/book

  • Hi Dave ~ we give a linear perspective since we're talking about time in this course. Human evolution itself isn't a simple linear (or progressive) process - many people conceptualize something like a tree: http://humanorigins.si.edu/evidence/human-family-tree
    Recent work showing interbreeding conceptualizes our recent origins being like a "braided stream"...

  • Great comments and questions ~ please do check out some of the reference material we posted for more details. I'll confess that trying to sum up 7 million years in less than 7 minutes was a tough task!

  • Yes Heslley ~ it is possible to teach and study evolution in a respectful way for people of all faiths or no faith. I often use this free downloadable pdf in my classes that makes it clear that "science and religion are different ways of understanding the world. Needlessly placing them in opposition reduces the potential of each to contribute to a better...

  • Hi folks ~ welcome to the course! This is such a dynamic topic and one that seems to pop up in the media pretty often. We're hopeful that by the end of these two weeks you'll be able to apply a more critical lens to what you may see in the news reported as "the oldest" or "the first" ~ and also appreciate that science also "evolves" or changes through time.