Primate Quadrupedalism: How and Why Does It Differ from That of Typical Quadrupeds?

The mammalian humeral retractors latissimus dorsi, teres major and caudal parts of the pectoral muscles are commonly thought to contribute to forward impulse during quadrupedal locomotion by pulling the body over the supporting forelimb. While most electromyographic studies on recruitment patterns for these muscles tend to support this functional interpretation, data on muscle use in chimpanzees and vervet monkeys have suggested that the humeral retractors of nonhuman primates are largely inactive during the support phase of quadrupedal locomotion. In the chimpanzee and vervet monkey, in contrast to what has been documented for other mammals, the contributions of latissimus dorsi, caudal pectoralis major, and teres major during quadrupedal locomotion are restricted to slowing down the swinging forelimb in preparation for hand touchdown and/or retracting the humerus to help lift the hand off the substrate at the initiation of swing phase. Based on these results, it has been proposed that unique patterns of shoulder muscle recruitment are among a set of characteristics that distinguish the form of quadrupedalism displayed by nonhuman primates from that of other nonprimate mammals. However, two primate taxa is a limited sample upon which to base such far-reaching conclusions. Here we report on the activity patterns for the humeral retractors during quadrupedal walking in an additional eight species of nonhuman primates. There is some variability in the activity patterns for latissimus dorsi, caudal pectoralis major and teres major, both between and within species, but in general the results confirm that the humeral retractors of primate quadrupeds do not contribute to forward impulse by pulling the body over the supporting forelimb.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Humeral retractor EMG during quadrupedal walking in primates

Larson

Stern

2007

“…In addition to those features described, it has also been reported that primates almost never adopt a running trot or pace (Demes et al, 1990;Demes et al, 1994;Hildebrand, 1967;Preuschoft and Gunther, 1994;Rollinson and Martin, 1981;Schmitt, 1995;Vilensky, 1989). Some have argued that primates eschew these gaits in order to avoid abrupt changes in vertical oscillations of the body and high peak ground reaction forces (Demes et al, 1990;Demes et al, 1994;Schmitt, 1999).…”

Section: Introductionmentioning

confidence: 98%

“…The quadrupedal locomotion of primates is unusual among mammals in many ways (Cartmill et al, 2002;Cartmill et al, 2006;Demes et al, 1994;Hildebrand, 1967;Kimura et al, 1979;Larson, 1998;Larson et al, 2000;Larson et al, 2001;Lemelin and Schmitt, 2006;Lemelin et al, 2003;Rollinson and Martin, 1981;Schmitt, 1999;Schmitt and Lemelin, 2002;Vilensky, 1989;Vilensky and Larson, 1989). The features that distinguish the walking gaits of primates include the prevalence of diagonal-sequence gaits (in which the contact of each hindfoot is followed by that of the contralateral forefoot), the use of highly protracted arm positions at forelimb touchdown, and relatively higher vertical peak forces on the hindlimb compared to the forelimb.…”

Section: Introductionmentioning

confidence: 99%

Adaptive value of ambling gaits in primates and other mammals

Schmitt

Cartmill

Griffin

et al. 2006

130

SUMMARY At speeds between the walk and the gallop, most mammals trot. Primates almost never trot, and it has been claimed that they transition directly from a walk to a gallop without any distinctive mid-speed running gait. If true,this would be another characteristic difference between the locomotion of primates and that of most other quadrupedal mammals. Presently, however, few data exist concerning the actual presence or absence of intermediate-speed gaits (i.e. gaits that are used between a walk and a gallop) in primates. Video records of running in twelve primate species reveal that, unlike most other mammals, all the primates studied almost exclusively adopt an `amble' -an intermediate-speed running gait with no whole-body aerial phase - rather than trot. Ambling is also common in elephants and some horses, raising the question of why ambling is preferred over trotting in these diverse groups of animals. Mathematical analyses presented here show that ambling ensures continuous contact of the body with the substrate while dramatically reducing vertical oscillations of the center of mass. This may explain why ambling appears to be preferable to trotting for extremely large terrestrial mammals such as elephants and for arboreal mammals like primates that move on unstable branches. These findings allow us to better understand the mechanics of these unusual running gaits and shed new light on primate locomotor evolution.

“…Experimental data, in conjunction with anatomical data on early human ancestors, show clearly that a relatively stiff modern human gait and associated physiological and anatomical adaptations are not primitive retentions from a primate ancestor, but are instead recently acquired characters of our genus. Larson, 1998;Larson et al, 1999Larson et al, , 2001 All K TQ, AQ Lemelin and Schmitt, 1998 All K TQ, AQ Reynolds, 1985 All T, FP TQ Reynolds, 1987 All T, K TQ, TB Vilensky, 1987, 1989Vilensky and Gehlsen, All T, K, EMG TQ 1984;Larson, 1989 Aerts et al, 2000 Hom T TQ, TB Chang et al, 1997, 2000Bertram and Hom FP AS Chang, 2001D'Aout et al, 2002 Hom T, K TQ, TB Elftman, 1944;Elftman and Manter, 1935 Hom K, T TB Jenkins, 1972 Hom K TB Kimura, 1990Kimura, , 1991Kimura, , 1996 Hom T, En TQ Stern, 1986, 1987 Hom EMG TQ, AQ, R Larson et al, 1991 Hom EMG AS, TQ, R Larson, 1988R Larson, , 1989 Hom EMG AS Okada and Kondo, 1982;Okada, 1985 Hom EMG TB Prost, 1967Prost, , 1980 Hom K, T TQ, TB, VC Shapiro et al, 1997 Hom EMG, T TQ Stern and Larson, 2001 Hom EMG TQ, AS Stern and Susman, 1981 Hom EMG TQ, TB, VC Susman, 1983 Hom K TQ, TB Swartz et al, 1989 Hom BS AS Tardieu et al, 1993 Hom K TB Tuttle and Basmajian, 1974a,b,c, 1977…”

mentioning

confidence: 99%

Insights into the evolution of human bipedalism from experimental studies of humans and other primates

Schmitt

2003

253

146

SUMMARYAn understanding of the evolution of human bipedalism can provide valuable insights into the biomechanical and physiological characteristics of locomotion in modern humans. The walking gaits of humans, other bipeds and most quadrupedal mammals can best be described by using an inverted-pendulum model, in which there is minimal change in flexion of the limb joints during stance phase. As a result, it seems logical that the evolution of bipedalism in humans involved a simple transition from a relatively stiff-legged quadrupedalism in a terrestrial ancestor to relatively stiff-legged bipedalism in early humans. However, experimental studies of locomotion in humans and nonhuman primates have shown that the evolution of bipedalism involved a much more complex series of transitions, originating with a relatively compliant form of quadrupedalism. These studies show that relatively compliant walking gaits allow primates to achieve fast walking speeds using long strides, low stride frequencies, relatively low peak vertical forces, and relatively high impact shock attenuation ratios. A relatively compliant, ape-like bipedal walking style is consistent with the anatomy of early hominids and may have been an effective gait for a small biped with relatively small and less stabilized joints, which had not yet completely forsaken arboreal locomotion. Laboratory-based studies of primates also suggest that human bipedalism arose not from a terrestrial ancestor but rather from a climbing, arboreal forerunner. Experimental data, in conjunction with anatomical data on early human ancestors, show clearly that a relatively stiff modern human gait and associated physiological and anatomical adaptations are not primitive retentions from a primate ancestor, but are instead recently acquired characters of our genus.