Mexican Footprints

“if an amaz­ing new dis­cov­ery is found I prob­ably will have noth­ing to say about it” I’m used to being proved wrong, but it would be nice to get through 24 hours before it hap­pens. After post­ing this on July 5, I flicked across to the BBC news site and found the item Footprints of ‘first Americans’ which is inter­est­ing in itself. What is more inter­est­ing is that these foot­prints are early.

Very early.

In fact they’re about 30,000 years earlier than the pre­vi­ous earli­est known evid­ence of occu­pa­tion of the Americas.

A foot and an ancient foot­print. Photo from the Mexican Footprints media sec­tion.

The foot­prints are from vol­canic ash lay­ers by a vol­cano in Mexico. This may seem odd. The favoured the­ory is that humans crossed into American via the Bering Straits. However the early occu­pa­tion of the Americas has a habit of appear­ing in awk­ward places.

The earli­est widely accep­ted human hab­it­a­tion site in the Americas isn’t in North America at all. It’s found at Monte Verde in Chile and dates to about 10,500 BC. There is another con­tro­ver­sial site in Brazil whose name I’ve sadly for­got­ten which dates to about 40,000 BC, but that’s been ignored as a poorly excav­ated site. We know it’s poorly excav­ated because it was dated to a freak­ishly early time. The reason assumed for find­ing sites so far south is two fold. The north­ern sites may not have sur­vived the ice age. The main­stream would also say that the spread to what is now Chile shows that early peoples moved very quickly down the coast.

A map of pro­posed routes for American col­on­isa­tion. Taken from the Mexican Footprints media sec­tion.

It still doesn’t explain why the lack of sites in the north well. The strongest reason for push­ing Bering Strait col­on­isa­tion is that the other explan­a­tions seem implaus­ible to most archae­olo­gists and the Bering Strait is the default choice. If these foot­prints prove to be accur­ately dated then it would sug­gest that archae­olo­gists need to exer­cise their brains a bit more.

One pos­sible reason for this impasse may be an unchal­lenged Eurocentric assump­tion about col­on­isa­tion. A lot of early col­on­isa­tion the­ory is based on how Europe came to be col­on­ised, which sug­gests Europe was a goal rather than a back­wa­ter for col­on­ists. No one is sug­gest­ing that Europe was the con­scious tar­get of peoples who had no idea of what the world was like and didn’t even know of Europe. Simply that Europe is the nicest part of the world. It has a pleas­ant cli­mate and nice anim­als and so on, so more people would be attrac­ted north. The Romans and Greeks both had a sim­ilar view of the world. They were in per­fect place because it was neither too cold nor too hot and was per­fect for grow­ing olives or figs. So they must have lived at the centre of the world.

This view of col­on­isa­tion is being chal­lenged. The recent pub­lic­a­tion in Science argues that early col­on­isa­tion went along an east-west axis faster than north-south. Why? East-west would take col­on­isers into broadly sim­ilar eco­lo­gical envir­on­ments. Foods should be sim­ilar to what is already known, so it’s the easier path. There are also mech­an­ical advant­ages. To take a wildly ana­chron­istic example the Polynesians found it much easier to col­on­ise east-west because of cur­rents and winds than north-south. This is why Easter Island which is ter­ribly remote was col­on­ised before New Zealand. Frustratingly I’ve lost the web address of a news page where an Australian stu­dent was happy to be an excav­a­tion in the UK because “they didn’t have a lot of his­tory” in Australia. Modern humans col­on­ised Australia about 50,000 years ago, or about twice as long as they’ve been in the British Isles.

So all ter­ribly excit­ing, but even more so when you see what the dis­cover­ers have done with the inform­a­tion. They’ve put up a pretty com­pre­hens­ive web­site at http://​www​.mex​ic​an​foot​prints​.co​.uk/ which not only has pic­tures, but also explains why this dis­cov­ery is so excit­ing by pla­cing it in the con­text of what we already think about American colonisation.

Now so far I haven’t seen the news pick up on what I thought would be the obvi­ous ques­tion. They may have been humans, but are these the foot­prints of Homo Sapiens? If there are non-Sapiens com­munit­ies in Indonesian from 15,000 years ago should be auto­mat­ic­ally expect the first human col­on­isers of North America to be mod­ern humans?

Who made the foot­prints? Image copy­right Bournemout University. Photo from the Mexican Footprints media sec­tion.

Counter to this is John Hawks’s com­ment from six months ago: “Out of Africa” jumps the shark?. There another take on the story at New Scientist.

Update around midday:

Further blogs dis­cuss­ing this are:


When he's not tired, fixing his car or caught in train delays, Alun Salt works part-time for the Annals of Botany weblog. His PhD was in ancient science at the University of Leicester, but he doesn't know Richard III.

3 Responses

  1. July 6, 2005

    Mexican Footprints

    More on the Mexican Footprints

    My post yes­ter­day on those Mexican foot­prints got a nice men­tion at a blog called Alun, which is writ­ten by an archae­oastro­nomy PhD stu­dent at the University of Leicester in the UK. He has a very thor­ough post about the…

    AUTHOR: Debi
    My father has also found foot­prints and no one seems to take his ser­i­ous on the mat­ter, any­one wish­ing to see them may con­tact him thru me at my e-mail address

    AUTHOR: alun
    I’m not sure if many archae­olo­gists will take these foot­prints seriously.

    One prob­lem is how con­vin­cing is a foot­print? While I was dig­ging in Luxembourg, someone work­ing in the same pit as me found a foot­print. It looked for all the world as though it was a foot­print. Was that wall built by a one-legged Roman? One of the prob­lems in work­ing out if some­thing like that is real is that even by chance if you scrape enough soil you should see some­thing con­vin­cing. It’s a bit like look­ing for shapes in clouds. So the more foot­prints you find the better.

    I’ll be hon­est if I were doing the press release I’d take the photo of the most con­vin­cing foot­prints. If the one up there is the best they can do then there may be a prob­lem. A lot of foot­prints would be needed to be convincing.

    There’s also the mat­ter of con­text. How can you date the foot­prints? This argu­ment is going to go on for a long time. In the Mexico case they’re geo­lo­gic­ally dated which, you’d think, was sound. However a lot of archae­olo­gists simply don’t under­stand geo­logy, so there’ll be a stream of quibbles as archae­olo­gists try and think of ways the dat­ing is wrong.

    There also seems to be a lack of asso­ci­ated arte­facts. In the time since this work was done I haven’t heard of any tools from the same period being found. It’s too early for this to be a major prob­lem, but it is peculiar.

    I’ll write up a reply on Debi’s prob­lem soon, as with more thought I think it’s an inter­est­ing dif­fi­culty. If you do find some­thing weird how do you get taken seriously?

  2. August 31, 2005

    Mexican Footprints

    […] No proper post today. I did want to put up some­thing on Debi’s ques­tion about how do you get someone to take a claim ser­i­ously if you’re not an aca­demic. The answer’s tak­ing a fair amount of thought so it won’t be up today. I’ve not even got any­thing scanned from Star-Names at the moment. I have about 3/4 of Aquarius ready, but it’ll take quite a bit of reset­ting with Greek typo­graphy and so on, so that might not resume until the weekend. […]

    AUTHOR: Al
    if you are int­res­ted i will send a photo of a per­fect left foot impres­sion over 22′ long, and sev­eral ankle impres­sion near by which would be idle for car­bon dat­ing. This is debi’s father, the one who had pos­ted earlier Aug 27, 2005 if you would like to con­tact me about these photo send and email to my address.

  3. December 2, 2005

    Mexican Footprints

    […] The dat­ing of the Mexican foot­prints is prov­ing to be a prob­lem. This week in Nature the foot­prints are the sub­ject of a Brief Communication Geochronology: Age of Mexican ash with alleged ‘foot­prints’. I’ve added two recent press release from Berkeley and Texas A&M on re-dating the prints. They tackle quite a prob­lem, how do you sample an absence of some­thing to get a date? […]

    AUTHOR: just­passin
    HOT OFF THE PRESS! mex­ico foot­prints paper now avail­able in the ‘in press’ sec­tion of Quaternary Science Reviews Journal (I dont have the URL to hand cos i was using a uni­ver­sity lib­rary subscription).

    there’s an inter­st­ing ‘note added in press’ sec­tion which back­tracks a lot, call­ing them ‘poten­tial’ foot­prints where the main body of the text never doubts they are foot­prints, but it does briefly deal with the 1.3My Ar-Ar date .

    Strange, but it looks like they simply paid for com­mer­ical dat­ing. None of the authors are dat­ing experts and the acknow­ledge­ments are stuffed full of thanks to people who helped with the dating.

    its not clear when it will be published

    AUTHOR: alun
    Thanks. I can access it from home, so there’s no excuse for me no to parade my ignor­ance as the dat­ing argu­ments get detailed. :)

    I’ve made a note of it so I’ll try and have a closer read­ing of the art­icle tomorrow.

    AUTHOR: just­passin
    I man­aged to see one of the ‘foot­prints’ experts a few days ago in a lec­ture she gave about the peopling of the amer­icas. She men­tioned the foot­prints, although it seemed clear that the dat­ing was not com­pletely firm at the moment. The key seems to be another sec­tion they have dis­covered which show the ash and a com­plete sequence of sed­i­ments above. I couldnt catch the whole argu­ment, but appar­ently the dates that were pub­lished may be from another area of the site and not dir­ectly related to the foot­prints! This new sec­tion has the ash and more sed­i­ments to date.

    This seems to be a big back­track to me. Why are they still dat­ing sed­i­ments if they are so sure of the age in the QSR article?

    Its inter­est­ing to me that the debate is all about the age of these so-called foot­prints. I’d be happy with any age for them provided someone could demon­strate they were *really* human foot­prints. Has any bio­met­rics expert gone on the record with an opinion?

    AUTHOR: alun
    I have to admit I’ve read a copy of the paper, but I still want to sit down with a geo­lo­gist who can help me with the bits I don’t understand.

    I agree that the iden­ti­fic­a­tion of whether or not these are foot­prints is an issue. If the American team are right and the date is a lot older then it doesn’t remove the prob­lem. Instead it gives you a human or ape in the New World at 1.3 Mya.

    Unfortunately I’m still a bit too busy to pur­sue this. One of the immin­ent dead­lines includes a paper I’m writ­ing for the National Astronomy Meeting on the prob­lems of recog­nising pat­terns in what might be ran­dom data.