The Order of Man: A Biomathematical Anatomy of the Primates

CHAPTER 6 Lower Limbs and Leaping

CHAPTER 6 Lower Limb s an d Leapin g Abstract — Wha t i s leaping ? Essay s int o biomechanic s Anatomy o f vertebrat e leapin g - Leapin g i n Primate s The structura l variet y o f prosimia n leaper s Is prosimia n leapin g eve n mor e complex ? New studie s o f leapin g behaviou r i n prosimian s New studie s o f leapin g anatom y i n prosimian s Morphometric studie s o f overal l lim b for m i n prosimian s Morphometric studie s o f th e prosimia n hi p an d thig h A diversio n int o testin g - A diversio n int o siz e Functional implication s o f thes e result s - Highe r primat e locomotio n Morphological mode s i n highe r primate s Univariate results , pelvis , talus , lowe r lim b Multivariate results , pelvis , talus , lowe r lim b Lower limb s - Taxonom y — Summary Abstract. In thi s chapte r w e discus s for m an d functio n i n primat e lowe r limbs . Becaus e leapin g i s s o obviou s a n adaptation o f many primates , an d becaus e leapin g has , therefore , bee n ver y wel l studied , w e first concentrat e upo n leaping species . Th e mos t marke d leaper s amon g th e primate s ar e al l prosimians . As in the case of the upper limb, early simpler views of leaping functions i n lower limbs did not differentiate betwee n the possibilit y o f the existenc e o f different form s o f leaping. Ne w natura l histor y studie s ar e startin g t o suggest tha t leaping i s carrie d ou t i n quit e differen t way s b y differen t animals . A s a resul t w e ca n envisag e th e averag e biomechanical situatio n (o f the fourth chapter ) fo r lowe r limb s a s a rathe r complexl y shape d spectru m o f function . We the n obtai n structura l description s o f various lowe r lim b parts (hip , thigh , overal l proportion s o f lower limb ) using the multivariate statistica l metho d of the third chapter . This also provides arrangements o f the prosimians tha t fall within a complex spectrum. A detailed vie w of the leg and foo t is not available because, apart fro m a few leg and foot dimension s withi n th e stud y o f overall proportion s o f the lowe r limb , thes e area s hav e no t bee n studied . The degre e o f concordanc e betwee n th e functiona l an d structura l spectr a i s examined ; th e tw o ar e remarkabl y similar. Th e overal l structur e o f the variou s part s o f the prosimia n lowe r limb , whe n viewe d quantitatively , speak s most clearl y abou t overal l function . We also carry out the equivalent procedure for the primates as a whole. In thi s case the functional spectru m is even more complex because it includes not only those species that leap in their different ways , but also a series of species that do quite differen t thing s wit h thei r lowe r limbs (e.g . hang upsid e dow n o n occasion : saki monkey s an d orang-utans ; walk on tw o legs habitually: humans ; run terrestriall y for mos t of the time: baboons an d pata s monkeys) . Again, th e structural spectr a ar e determine d usin g multivariat e statistica l studie s o f th e hip , thigh , ankle , foot , an d overal l proportions o f th e lowe r lim b a s a whole . I t i s once agai n remarkabl y concordan t wit h th e spectru m derive d fro m considerations o f function . The chapter ends with a caveat about the apparent systematic content of the morphological data; it does indeed exist though no t a s clearl y a s th e functional . Thi s is , again , a stor y t o...