Perceived protein needs and measured protein intake in collegiate male athletes: an observational study.

BACKGROUND: Protein needs for athletes are likely higher than those for the general population. However, athletes may perceive their protein needs to be excessively high. The purpose of this research was to compare collegiate athletes' perceived protein needs and measured protein intake to the recommended protein intake (RDI) for healthy adults (i.e. 0.8 g/kg/d) and to the maximum beneficial level for strength-trained athletes (i.e. 2.0 g/kg/day). METHODS: Perceived protein needs were quantified in 42 strength-trained collegiate male athletes by using a survey that asked the athletes to provide their perception about protein needs in specific quantitative terms (i.e. g/kg/d). Perceived protein needs were also determined by having the athletes select a daylong menu that they perceived to have adequate protein content from a collection of 5 isoenergetic menus, which differed in terms of protein content. Actual protein intake was quantified using 3-day food records and nutrient analysis. Single sample t-tests were used to compare protein intake and perceived protein needs to 0.8 g/kg/day and 2.0 g/kg/day. RESULTS: When asked to provide, in quantitative terms, protein needs for athletes, 67% of the athletes indicated "do not know." Of the remaining 33% of athletes, all gave values greater than 2.0 g/kg/d (mean 21.5 ± 11.2 g/kg/d, p = 0.14 vs. 2.0 g/kg/d). Based on the menu selection method for determining perceived protein needs, the athletes indicated that their protein needs were 2.4 ± 0.2 g/kg/d, which was greater than the RDI for protein (p < 0.0001) and tended to be greater than the maximally beneficial protein intake of 2.0 g/kg/d (p = 0.13). Measured protein intake was 2.0 ± 0.1 g/kg/d, which was greater than the RDI (p < 0.0001) but not different from the maximally beneficial protein intake of 2.0 g/kg/d (p = 0.84). CONCLUSIONS: Male collegiate athletes recognize that their protein needs are higher than that of the general population and consume significantly more protein than recommended in the RDI. However, it also appears that athletes are not aware of objective recommendations for protein intake and may perceive their needs to be excessively high. This study highlights the need for nutrition education in collegiate athletes, in particular nutrition education on macronutrient distribution and protein needs.

Coming of age: steroid hormones of wild immature baboons (Papio cynocephalus).

Large gaps exist in our knowledge about common patterns and variability in the endocrinology of immature nonhuman primates, and even normal hormonal profiles during that life stage are lacking for wild populations. In the present study we present steroid profiles for a wild population of baboons (Papio cynocephalus) from infancy through reproductive maturation, obtained by noninvasive fecal analyses. Fecal concentrations of glucocorticoid (fGC) and testosterone (fT) metabolites for males, and of fGC, estrogen (fE), and progestin (fP) metabolites for females were measured by radioimmunoassay (RIA). In males, infancy was characterized by high and declining levels of fGC and fT, whereas steroid concentrations were low during the juvenile years. During the months immediately prior to testicular enlargement, fT (but not fGC) concentration tended to increase. Males that matured early consistently had higher fT and fGC concentrations than those that matured late, but not significantly so at any age. Individual differences in fT concentrations were stable across ages, and average individual fT and fGC concentrations were positively correlated. For females, high and declining levels of fE characterized infancy, and values increased again after 3.5 years of age, as some females reached menarche by that age. Both fP and fGC were relatively low and constant throughout infancy and the juvenile period. During the months immediately prior to menarche, fGC concentration significantly decreased, while no changes were observed for fE levels. fP exhibited a complicated pattern of decrease that was subsequently followed by a more modest and nonsignificant increase as menarche approached. Early- (EM) and late-maturing (LM) females differed only in fP concentration; the higher fP concentrations in EM females reached significance at 4-4.5 years of age. Maternal rank at offspring conception did not predict concentrations of any hormone for either sex. Our results demonstrate the presence of individual endocrine variability, which could have important consequences for the timing of sexual maturation and subsequently for individual reproductive success. Further evaluation of the factors that affect hormone concentrations during the juvenile and adolescent periods should lead to a better understanding of mechanisms of life-history variability.

Intra-and interpopulational differences in orangutan (Pongo pygmaeus) activity and diet: implications for the invention of tool use.

Tool manufacture and use have been described for wild orangutans (Pongo pygmaeus), with appreciable interpopulational differences in tool complexes. The ecological factors that contribute to these differences require investigation. Significant interpopulational differences in diet suggest that ecological factors contribute to variation in tool-based insect foraging. Using 4 years of behavioral data from the Suaq Balimbing Research Station (Sumatra, Indonesia), we tested predictions of two ecological hypotheses for the invention of tool use for insect foraging. We found limited evidence for inter- and intrasexual differences, as well as temporal variation, in activity budget and diet. However, differences did not correspond to variation in either rate of tool use or specialization on tool-based insectivory. Compared to other populations, orangutans at Suaq Balimbing ate significantly more insects. Low temporal variation in insectivory and an abundance of social insects at Suaq Balimbing suggest that insects formed a staple in the diet rather than a fallback food. Our findings do not support the hypothesis that tool use is a response to the low availability of primary food sources. Rather, greater opportunities for invention likely contributed to insect-extraction tool use at Suaq Balimbing.

Individual variation in the rate of use of tree-hole tools among wild orang-utans: implications for hominin evolution.

Primate tool use varies among species, populations, and individuals. Individual variation is especially poorly understood. Orang-utans in the Sumatran swamp forest of Suaq Balimbing varied widely in rates of tool use to extract honey, ants or termites from tree holes and in the degree to which they specialized on this tree-hole tool use. We tested whether individual variation was best explained by effects of social dominance, habitat differences, or by opportunities for socially learning the skills during ontogeny. There was no evidence for the first two hypotheses. However, we found a strong relationship between tool use specialization and mean female party size, which was used as a proxy for the opportunities for socially mediated learning in a foraging context during their development. This use was justified because females are rather philopatric and their mean party size remained stable over time, thus reflecting long-term tendencies. The correlation was not an artifact of a direct effect of party size on tool use tendencies, and did not hold for males, the dispersing sex. Thus, variation in the number of opportunities for social learning explains tool use variation within populations, corroborating hypotheses for between-population variation. The emergence of human culture was accompanied by vastly improved mechanisms of social learning. In order for these improvements to be favored by natural selection, the cultural potential must have actually been expressed. Thus, a combination of strong sociability and a reliance on tool-using or other technical skills acquired through social learning must have characterized early hominins.

New tool use by wild Sumatran orangutans (Pongo pygmaeus abelii).

Two forms of tool use by wild Sumatran orangutans are reported from the Agusan Monitoring Station, a new research site in Indonesia. One form, a branch "hook" used in locomotion, has not been reported previously in wild orangutans. The second form, a leaf "pad" used to protect the hands and feet from thorns while feeding, shares similarities in form and function with a tool type used by orangutans at Ketambe, a nearby research site. Both instances of tool use occurred in areas of disturbance, and appear to be spontaneous inventions under novel conditions, although habitual use of the tool in other ecological contexts is plausible. A summary of the distribution of tool use types in wild orangutans is presented.