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Home , Australopithecine, Gigantopithecus, Lufengpithecus, Paranthropus

The RELICT HOMINOID INQUIRY 1:51-56 (2012)

From the Editor

ADAPTIVE RADIATIONS, BUSHY EVOLUTIONARY TREES, AND RELICT HOMINOIDS

Jeff Meldrum*

Department of Biological Sciences, Idaho State University, Pocatello, ID 83209-8007

Recent developments in Shortly thereafter, the hypothesis further have promoted a shift in attitude toward the retreated when it was recognized that African question of relict hominoids. Over a half erectus (now H. ergaster), a large- century ago, interpretations of the hominin brained ancestor, had coexisted with record were markedly different. () bosei, a Deriving from the influential evolutionary parallel lineage of small-brained facially concept of competitive exclusion (Gauss, robust hominins that presumably eventually 1934), as applied to (Mayr, went extinct (Leakey & Walker, 1976). These 1950), it was deemed that only one species display the expected ecological could occupy the hominin niche at any given reaction to a sympatric competitor, i.e. niche point in time. From this emerged the Single partitioning, involving diet, micro-habitat Species Hypothesis (Wolpoff, 1971). This divergence, and possibly also temporal hominin niche was associated with adaptations differentiation of resource use (Winterhalder, for habitual , reduced canines, tool 1981). Stephen J. Gould (1976) made a use, and culture. The latter was thought prediction in his popular column in Natural perhaps most significant, because with culture History, stating: “We know about three and the plasticity of learning, a species could coexisting branches of the human bush [Homo conceivably broaden its niche space, further habilis, , and Australopithecus reducing the potential for sharing the bosei]. I will be surprised if twice as many landscape with other hominins (but see more are not discovered before the end of the Winterhalder, 1981). century.” In 1976, Washburn and Ciochon challenged Indeed, mounting discoveries accumulating the reach of the hypothesis and opined that it at a steady pace, reveal dozens of hominin was not until the emergence of Homo erectus species spanning a seven million period that one species became so successful that all (see Tattersall, 1996, but see White, 2009). others were eliminated. They allowed that the The hominin phylogentic tree becomes preceding more “-like hominins,” i.e. the increasingly bushy with each additional , offered a radiation of species. This proliferation of species is not contemporary coexisting species (see Lewin & merely an artifact of taxonomic “splitters” vs. Foley, 2004). “lumpers.” Martin (1990) has estimated that a

*Correspondence to: Jeff Meldrum, Dept. Biol. Sci., Idaho State University, 921 S 8th Ave., Stop 8007, Pocatello, ID 83209-8007. email: [email protected]. © RHI

JEFF MELDRUM 52 mere 3% of past taxonomic diversity in reveal primitive anatomies reminiscent of H. paleocommunities has been habilis or Australopithecus, again leading recognized and documented in the fossil some to propose a pre-erectus African origin record. Assuming the same holds true for for the species (Tocheri et al., 2007; Jungers et hominins, and taking a conservative tally of a al., 2009; Morwood and Jungers, 2009). This dozen extinct hominin species, according to raises even more questions over hypotheses Martin’s estimate there could conceivably be about the origins of H. floresiensis and its 400 species of hominin as yet unknown. arrival on the Indonesian island of Flores. Given the particulars of the inferred natural Australopithecines are presently only known history of large-bodied , and from Africa. Did a late / early especially the tendencies for generalized Homo disperse across Asia without leaving behavioral ecology of hominins, such a high any record of its passage? This is certainly figure for hominin diversity seems rather under serious discussion. unlikely (Arcadi, 2006). It emphasizes Another hominin potentially exhibiting a however, that the currently known fossil more recent persistence then previously record likely underestimates past diversity. recognized is Asian Homo erectus. Dating of The perennial discovery of new hominin Homo erectus sites at the extreme of its range species attests to that expectation. in Southeast Asia has produced ages of 30-50 In addition to this growing appreciation of ka, suggesting possible contemporaneity with the bushiness of the hominin tree, there are modern H. sapiens arriving in the region revelations of the ever more recent persistence (Swisher et al., 1996). These younger dates of a number of the branches or lineages within were seemingly contradicted by a later study; the tree. One of the most surprising however the older dates could be attributed to discoveries was the enigmatic “Hobbit” or reworked sediments at the site (Indriati et al., . This diminutive hominin 2011). Should the younger dates be unearthed on the Indonesian island of Flores substantiated, this would prove a hominin has been dated to as recent as a mere 18 ka example of relative biogeographic isolation (Brown et al., 2004). The recognition of this and survival that parallels the persistence of startling species even prompted the editor of the last . to point out that since Homo The discovery of the Denisova hominins floresiensis survived until so very recent, it added another branch to the bush (Krause et was now more likely that stories of other so- al., 2010). The fragmentary date to called mythical, human-like creatures, such as only 30 ka and were recovered from a cave the are founded on grains of truth (Gee, site in southern Siberia, in the Altai Mountains 2004). He went on to acknowledge the near the Mongolian border. The completed possibility that the taxonomic and adaptive sequence of the Denisova hominin genome diversity of hominins was always high, has established this species as distinct from remained high until very recently, and might modern and Neanderthals (Reich et not be entirely extinguished. This was a al., 2010). The remains include remarkably notable concession reflecting a changing robust teeth and toe bones (Mednikova, 2011; attitude, although one generally not so openly Reich et al., 2010). The , if correctly displayed. identified as a third , is as large as that of The justification of the attribution of the an australopithecine. Green, one of the lead “Hobbit” to the Homo has been researchers contemplated, "…you have to questioned due to its small brain-size and wonder if there were other populations that primitive aspects of its skeleton (Meldrum, remain to be discovered.” 2004). Recent studies of wrist and foot bones That Neanderthals and modern Homo

BUSHY TREES 53 sapiens coexisted on the European continent documentary “Searching for the Ultimate for tens of thousands of has long been Survivor.” While middle hominins recognized. During this extensive period of were large, the Goliath moniker is an overlap they remained separate and distinct exaggeration (see Ruff et al, 1997). Whether populations. The sequencing of the Homo heidlebergensis’ range encompassed genome has revealed minimal eastern Asia is debated (Lu et al., 2011). introgression between the species (Green et However, a specimen of pre-modern hominin al., 2010; Currat and Excoffier, 2011). While recovered from the site of Lishu, on display at much press has been directed to this limited, Peking University, has a preliminary date of even trivial, gene flow, of even greater 12-20 ka (Lu, personal communication). implication is the flip-side to this observation Therefore, an observer of the Asian landscape – that such genetically similar species of only 20 ka could potentially encounter any remained almost entirely distinct in spite of of a half dozen hominin species coexisting millennia of contact. there. A new cave site in the Altai Mountains has The implication of the recognized bushy produced additional Neanderthal fossils, at the hominin tree was a major theme developed in most easterly known extent of their range, a Nova documentary series “Becoming with preliminary dates of only 10-20 ka Human.” The final episode, which introduced (Reich, personal communication). This is less modern humans, was titled “Last Human than half the previous latest occurrence for Standing: Many human species once shared Neanderthals previously documented – 28 ka, the globe. Why do we alone remain?” possibly as young as 24 ka (Delson and Introductory remarks addressed the singular Harvati, 2006). The geographic range for circumstance of Homo sapiens’ solitary Neanderthals may has increased in another inheritance of the world. The producers’ direction as well, with archeological evidence explanation for this situation echoed the suggesting they occupied the subarctic earlier pronouncement of Washburn and northern extent of the Ural Mountains in Ciochon (1976) on the supremacy of Homo Russia, some 33 ka (Slimak et al., 2011). Only erectus, by suggesting that in this case, Homo the recovery of skeletal remains will confirm sapiens were so successful that all other this site as Neanderthal. The possibility of hominins were eliminated from the scene. Neanderthal persistence into the present has This assertion may prove as unfounded for been examined in the scientific literature by Homo sapiens as it was for Homo erectus a Porshnev (1974), Bayanov and Bourtsev quarter century earlier. What was not (1976) and Shackley (1982). considered was the implication of the question Homo heidlebergensis (sometimes referred “Why do we alone remain?” — that is, why to as archaic Homo sapiens) were large and would the present be the exception to the rule robust pre-modern hominins considered the that has apparently prevailed throughout common immediate antecedents of modern hominin history? humans and Neanderthals. Some researchers The fossil record of has likewise grown have portrayed them as “giants” dubbing them into a very bushy tree. A remarkable “Goliath” in the popular literature taxonomic and adaptive diversity of ape (Kappleman, 1997). Lee Berger suggested that species is unfolding, with nearly 100 extinct Homo heidlebergensis populations routinely species throughout the and produced 7 foot tall individuals and (Begun, 2003; Cameron, 2004). We find apes reconstructed them accordingly with Steve associated not only with evergreen tropical Churchill for a National Geographic forests but also with swamps, grassland

JEFF MELDRUM 54 savannas, seasonal woodlands, and subtropical . This massive ape has been to even temperate habitats not usually referred to as the “fifth great ape” because it considered associated with preconceptions of had been the only species, other than those ape lifeways. We find a diversity of dietary now extant, recognized to have persisted well and correlated dental adaptations, with into the Pleistocene, until 250-300 ka Eurasian hominids displaying enamel molar (Cameron, 2004; Rink et al., 2008). The very thickness and canine reduction rivaling even real potential for the persistence of the most extreme morphologies of later Gigantopithecus into the recent has been African hominins, such as the robust acknowledged by past researchers such as australopithecines. We learn that the derived John Napier (1973), who observed, “It is ape form of locomotion, i.e., forelimb possible that these creatures, thought by suspension, must have evolved independently anthropologists to be long extinct, survived in in the Dryopithecinae, the modern African refuge areas such as some of the deep forested apes, and a third time in Pongo — a powerful river gorges of the Himalayan range until example of parallelism to consider when relatively recent times. The absence of a fossil contemplating the multiple evolutions and record is not necessarily evidence of derivations of bipedalism. And yet even this .” broadened perspective is inherently biased, As recently as 1998, Chris Stringer since representation in the fossil record is acknowledged that the yeti legend might not skewed toward those habitats most conducive be so far-fetched as often presumed, and may to fossilization and those strata subsequently indeed have been inspired by surviving uplifted and exposed to funded explorations. populations of Gigantopithecus. He allows There is a notable gap in the fossil record of that the giant ape may survive today in the apes for the past 5 million years. The extant dense forests of Southeast Asia. Stringer great apes are themselves merely relict species recognized that it would be wrong to assume in tropical forest refugia, poised on the brink that Gigantopithecus-like creatures could not of extinction. Virtually no immediate fossil survive to the present day without being antecedents of the African apes are known, discovered. “It could have survived until the with the exception of three isolated teeth of a appearance of modern humans 50,000 years fossil 500 ka (McBrearty and ago, and it is at least possible that it is still Jablonski, 2005). Sparse dental remains of living as a very rare creature in remote forest -like species are found throughout areas,” Stringer contemplated. On this matter, the Pleistocene of mainland southeast Asia David Begun noted, “There is no reason that (Zhao et al., 2009). The extant orangutan is such a beast could not persist today. After all now restricted to the islands of Borneo and we know from the sub-fossil record that Sumatra. -size lemurs lived on the island of Few additional species emerge from the gap. Madagascar until they were driven to An Asian “mystery ape” has been suggested extinction by humans only 1,000 years ago” as a newly recognized member of the mid- (Begun, 2003). Pleistocene Stegedon-Ailuropoda fauna There are numerous isolated specimens that (Ciochon, 2009). However this may be less are suggestive of as yet unrecognized species. mysterious than proposed and instead be a late We have likely only begun to scratch the survival of , or a closely related surface. Is the five million year gap in the ape descendant form (Etler et al., 2001; Etler, record actually the demise of this radiation? 2009). Obviously the progenitors of the extant great The only other ape currently recognized in apes bridge the gap, although we have very the Asian Stegedon-Ailuropoda fauna is little to show for it. As for extant species —

BUSHY TREES 55 the Bili (or Bondo) ape is remindful that the American 289(2):74-83. discovery of the mountain gorilla in 1902 Berger. http://www.thenakedscientists.com/HTML/ content /interviews/interview/833/. could well be repeated. In this instance, Brown P, Sutikna T, Morwood M., Soejono RP, genetic testing determined that the Bili ape is Jatmiko, Wayhu Saptomo E and Rokus Awe Due a known subspecies of chimpanzee, (2004). A new small-bodied hominin from the Late troglodytes schweinfurthii, although a Pleistocene of Flores, Indonesin. Nature 431 (7012): population that is exceptionally large and 1055–106. Cameron DW (2004) Hominid Adaptations and displays a unique culture with many habits . Sydney: University of New South Wales similar to those of (Hicks, in press). Press. Certainly it is possible that Homo sapiens is Ciochon RL (2009) The mystery ape of Pleistocene indeed the last hominin standing; likewise, Asia. Nature 459:910:911. that gorillas, chimps, bonobos and Currat M and Excoffier L (2011) Strong between humans and Neanderthals inferred are the last apes standing, or hanging as the from observed patterns of introgression. PNAS case may be. Extinction happens. But if we 108(37): 15129-15134. are to learn from history, and recognize the Delson E and Harvati K (2006) Paleoanthropology: implications of the growing bushiness of the Return of the last Neanderthal. Nature 443:762-763. hominoid tree, combined with the recent Etler D (2009) Mystery ape: Other fossils suggest it’s no mystery at all. Nature 460:684. persistence of several of its branches, then the Etler DA, Crummett TL, Wolpoff MH (2001). possibility of relict hominoids should not be Longgupo: Early Homo colonizer or Late Pliocene dismissed out-of-, particularly when Lufengpithecus survivor in South China? Hum Evol evidence – suggestive at least, if not yet 16:1-12. definitive – accumulates to that end. Gee H (2004) Flores, God and Cryptozoology. Nature 431: 1055-1061. Could a relict pre-modern hominin, e.g. Gould SJ (1976) Ladders, bushes, and human evolution. Homo neandertalensis, or Homo denisova, be Natural History 85(4):24-31. the explanation for the Russian almas? Could Green, RE, Krause J, A. W. Briggs AW et al. (2010) A a relict ape, e.g. Lufungpithecus, be the draft sequence of the Neandertal genome. Science explanation for the yeti of the subtropical 328(5979):710–722. Green. http://www.physorg.com/news/2010-12-fossil- forests of the Himalayas? Could a relict finger-bone-yields-genome.html. australopithecine be the explanation for the Hicks TC (in press). Encounters with Bili orang pendek in southeast Asia? Could in the undisturbed Gangu Forest. In Among African Gigantopithecus, or some hominin, e.g. apes: Stories and photos from the field. MM. Paranthropus, be the explanation for the Robbins and C Boesch (eds.) Berkeley: University of California Press. Chinese , or the North American Indriati E, Swisher CC III, Lepre C, Quinn RL, sasquatch? In the context described above, Suriyanto RA, et al. 2011. The age of the 20 meter these are legitimate and timely questions Solo River Terrace, , Indonesia and the survival worthy of the serious consideration of the of Homo erectus in Asia. PLoS ONE 6: e21562 anthropological community. Thus the birth of Kappelman J (1997). They might be giants. Nature 387:126-127. the RHI. Leakey REF and Walker AC (1976) Australopithecus, Homo erectus and the single species hypothesis LITERATURE CITED Nature 261:572-574. Lu Z, Meldrum DJ, Huang Y, He J, Sarmiento EE Arcadi AC (2006) Species resilience in Pleistocene (2011) Pedal skeleton of the Jinniushan hominin hominids that traveled far and ate widely: An analogy from the Middle Pleistocene of China. Homo 62:389- to wolf-like canids. J Hum Evol 51:383-394. 401. Bayanov D, Bourtsev I (1976) On Neanderthal vs. Martin RD (1990) Primate Origins and Evolution: A Paranthropus. Current Anthropology 17(2):312-318. Phylogenetic Reconstruction. Princeton, NJ: Begun DR (2003) Planet of the apes. Scientific Princeton University Press.

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