Thursday, July 2, 2009

Bigfoot or Mistaken Identity?

Ecological Niche Modeling is a great tool for conservation biology, phylogeography and evolutionary biology. However, as Jeff Lozier and colleagues point out in a paper in Journal of Biogeography, the models are only as good as the data they are based on.

The basic premise of the ENM approach is to predict the occurrence of species on a landscape from georeferenced site locality data and sets of spatially explicit environmental data layers that are assumed to correlate with the species’ range.
This is fine if the researchers themselves collect the data, but many studies rely on publicly available online databases. While no doubt the validity of most of this data is unimpeachable, there can be instances of misidentification or poor taxonomy. These discrepancies have the potential to significantly skew the results. As an extreme example, the authors point to Sasquatch, the North America's purported other large primate. Using data from the Bigfoot Field Researchers Organization, Lozier et al. predict the Sasquatch's range in the Western US (see figure above).
(T)he ENM shows that Bigfoot should be broadly distributed in western North America, with a range comprising western North American mountain ranges such as the Sierra Nevada Mountains, the Cascades, the Blue Mountains, the southern Selkirk Mountains, and the Coastal Range of the Pacific Northwest.
Interestingly, Bigfoot's supposed range overlaps considerably with another large American mammal, Ursus americanus, the Black Bear. Naturally, it is quite possible that the Black Bear and Sasquatch could share similar habitat requirements, but perhaps a more parsimonious hypothesis is that Black Bears are being misidentified as Sasquatch.
Thus, the two ‘species’ do not demonstrate significant niche differentiation with respect to the selected bioclimatic variables. Although it is possible that Sasquatch and U. americanus share such remarkably similar bioclimatic requirements, we nonetheless suspect that many Bigfoot sightings are, in fact, of black bears.

Photo of mangy bear
The take-home message is that scientists should carefully scrutinze literature records and/or public databases. Validate taxonomy. Rely on recognized experts. Don't be afraid to disregard questionable specimens. Ecological Niche Modeling has a bright future, but like any technique it can be properly or improperly applied. The authors should be commended for their clever approach to pointing out the need for scrutiny.

Lozier, J., Aniello, P., & Hickerson, M. (2009). Predicting the distribution of Sasquatch in western North America: anything goes with ecological niche modelling Journal of Biogeography DOI: 10.1111/j.1365-2699.2009.02152.x


  1. hey thanks for the post! we appreciate it. mike and i work on real organisms with real conservation concerns, so we hope this paper helps...

  2. 16th International Congress of the International Union of Anthropological and Ethnological Sciences (IUAES)

    By Drs Aris and Daphne N. Poulianos
    Kunming, China 31-7-09

    The title of this paper may sound a little deterministic, but I am convinced we human beings went through a longer period of hominization, than usual historians, including marxists, allow to conclude today.
    We definitely come from apes, but not African ones. Once upon a time lived in Europe over fifty species of monkeys. But an ape, which I named Helladopithecus semierectus, lived on trees, seventeen million years ago (ANTHROPOS, V3, N01, Jan. 1976, pp3 – 30, Athens).
    The well known Pikermi fauna of the Miocene period is found from Hungary through Balkans to Iran: (Wagner, A1840: Fossile Uberreste Von einem Affen und anderensau getierren aus Griechenland. Abh. Bayer. Akad. Wiss, 3, Munchen). Among other finds, a very important of that period was Mesopithecus pentelici, whose range also extended over a large territory, beyond Greece, and which is known to be a terrestrial monkey. It’s wide extension over a large territory, presupposes, that some anthropomorphic monkeys could ’’descend from trees’’ (Roghinski, J.J. & M.G. Levin, 1963: Anthropologhia, Moskva, str. 184 – 185), and begun to walk. Consequently among those “descenders” could be some andecedent forms of man.
    Another lower jaw from Attica found by a german officer during the years of occupation (1942) and described by G.Von Koenigswald, (1972: Einunterkiefez eines fossilen Hominoiden aus dem unterpliozan Griechenlands. Konikl. Nederl. Akademie Van Wetenschappen. Series B, 75, No 5, str. 385 – 394, Amsterdam), seems to be an advanced form which does not belong to Dryopithecinae, and which might also represent the beginning of African Primates. Koenigswald gave him a not very successful name “graecopithecus”. Its age is about 9 million years old. The lower jaw of another specimen found by the French expedition in 1972 near Thessaloniki, was named Dryopethicus macedoniensis. But it is also of a more advanced type than the Dryopithecinae, and according to Koenigswald is more closely affiliated with the hominids. Its age is Upper Miocene (Vallesian).
    Finally, the find described in this paper (Helladopithecus), is the upper part of a left femur found by our expedition in 1974 near Tharounia, a village in the island of Euboea. The age established lately, is Lower Miocene, about 17 million years old, confirmed by its stratigraphy, as well, and kept now in the Anthropological Museum of the Archanthropus man at Petralona, Chalkidiki.
    It is fully described and decided to be a semierectus monkey, as these authors call the whole complex of similar finds from Attica and Makedonia too.
    The new bone find is 98 mm. long (given the signal name ‘’A.E. – 1’’, seems to belong to a rather young individual, and its whole length (proportionally counted) cannot be more than 350 mm. That is the standing height should be about 140-150cm. Its weight, according to Debetz index (ICVS), approximately should be about 40-42 klgms. The stoutness index then is about 22, 85 (the same index for Orang, Chimpanzee and Gorilla, being 32-33, while for man is 18-21.

  3. 16th International Congress of the International Union of Anthropological and Ethnological Sciences (IUAES)

    But among all these indirect methods of identifying a find, the best would be to measure exactly the Torsion angle, in order to establish the percentage of its erect position. Thus a new method was developed to measure the torsion angle in a broken femur bone. This method is based on the assumption that the torsion angle (Θ) of a bone is directly proportional to the angle of its cylindrical surface (α). (See designs 2 and 3). The axis of a bone is the line passing through all gravity centers of all its side section (AB). The edge of the cylindrical surface of a bone is the line uniting all corresponding corners of the cross – section (ΓΔ). That is: θ=Κ.α, where Κ – proportionality coefficient.
    And this assumption is based on
    a)the geometrical similarity of corresponding bones of different animals.
    b)The physico-chemical similarity of bones, and
    c)On the approximately constant ratio between animal weight and cross-sectional area, that is the stress of bone loading is almost constant (the animal weight per unit of cross-sectional bone area).
    In order to find Κ we take a similar unbroken contemporary bone, and measure its angles θ and α:
    Κ= θ. Unbroken / α. unbroken
    Then we measure the angle α of the broken bone and find angle
    θ.broken = K.a unbroken = θ. Unbroken . α. broken / α. unbroken
    Angle α is the average of angles β & γ.
    The angles β & γ can be found by photographing the bone and measuring these angles on the picture. In order to make edge ΓΔ clearly distinguishable we illuminate the bone from the side. Then ΓΔ becomes the border line of two differently illuminated surfaces. In our case we took 17 differently oriented pictures of both bones, broken and unbroken (see pictures in the text and table 1).
    The result of these procedures showed that θ (torsion) broken = 18ο , which means that this monkey was about 65% erect during his lifetime. That means he was pretty much erect, certainly more erect than most today’s African primates. Thus, it is concluded, Helladopithecus could be the forerunner of Homo.
    Finally, we raise to the rank of a separate family the whole complex of Helladopithecus finds from Greece, classifying it right after the Hominid family. As a result of the above process we have the first standing man on earth, Homo erectus trilliensis, spreading all over the world from this region of the Aegean, of the SE of Europe 13 million years ago.
    The over one hundred years long discussion among anthropologists (‘’polyphyletic versus monophyletic origins’’) sounds is ending. Monophyletic origin of man (from Helladopithecus to Homo erectus trilliensis) to our opinion is more or less confirmed who spread from Atlantic to Pacific and then all over the rest of the world. It seems every biological species on earth develops from one center, and then it spreads all over.
    In the mean time excavations are going on: A new find, a part of the skeleton of a young girl of 14 years old was found. The find was named Homo erectus trilliensis Daphnae, after the name of the lady present in this hall Mrs Daphnae A.Poulianos.