Caloric Benefits Research Articles

The cost of cooking for foragers

Cooked food provides more calories to a consumer than raw food. When our human ancestors adopted cooking, the result was an increase in the caloric value of the diet. Generating the heat to cook, however, requires fuel, and accessing fuel was and remains a common problem for humanity. Cooking also frequently requires monitoring, special technology and other investments. These cooking costs should vary greatly across multiple contexts. Here I explain how to quantify this cooking trade-off as the ratio of the energetic benefits of cooking to the increased cost in handling time and examine the implications for foragers, including the first of our ancestors to cook. Ethnographic and experimental return rates and nutritional analysis about important prey items exploited by ethnohistoric Numic foragers in the North American Great Basin provide a demonstration of how the costs of cooking impact different types of prey. Foragers should make choices about which prey to capture based on expectations about the costs involved to cook them. The results indicate that the caloric benefit achieved by cooking meat is quickly lost as the cost of cooking increases, whereas many plant foods are beneficially cooked across a range of cooking costs. These findings affirm the importance of plant foods, especially geophytes, among foragers, and are highly suggestive of their importance at the onset of cooking in the human lineage.

Constraining the Likely Technological Niches of Late Middle Pleistocene Hominins with Homo naledi as Case Study

We develop a framework to differentiate the technological niches of co-existing hominin species by reviewing some theoretical biases influential in thinking about techno-behaviours of extinct hominins, such as a teleological bias in discussing technological evolution. We suggest that some stone-tool classification systems underestimate technological variability, while overestimating the complexity of the behaviours most commonly represented. To model the likely technological niches of extinct populations, we combine ecological principles (i.e. competitive exclusion) with physical anthropology and the archaeological record. We test the framework by applying it to the co-existence of Homo naledi and Homo sapiens during the late Middle Pleistocene in southern Africa. Based on our analysis, we suggest that tool use was probably not an essential part of H. naledi’s niche, but that technology occasionally provided caloric benefits. In contrast, tool use was a structural part of the H. sapiens way of life. We provide reasoning for our interpretation that the latter population is associated with more sophisticated reduction strategies and the development of prepared core technology. The method also has applicability to cases such as the co-existence of different toolmakers during the Earlier Stone Age (ESA) in East Africa and the co-existence of Neanderthals and H. sapiens in Eurasia.

Are American black bears in an agricultural landscape being sustained by crops?

AbstractHuman-altered landscapes are thought to reduce habitat quality for many forest-dependent species, but some omnivorous, opportunist species take advantage of human-related food sources, such as garbage and crops. It is unknown, however, whether anthropogenic foods can sustain populations in areas with relatively little natural habitat. We studied (2007–2012) a population of American black bears ( Ursus americanus ) at the western periphery of their range in Minnesota, in a landscape that was heavily impacted by agriculture (~50%). We estimated the dietary contributions of corn and sunflowers (2–4% of the landscape) versus seasonally available natural foods (spring vegetation, ants, deer, fruit, and nuts) with stable isotope analyses (δ 13 C and δ 15 N) of 110 hair samples from 51 bears. We identified associations between diet and sex, age, body size and condition, reproductive status, space use, habitat connectivity, and natural food abundance. At the population level, adult males and adult females without cubs consumed considerable crops in fall (95% credible intervals: males = 19–46% of diet, females = 10–40%), but females with cubs and juvenile bears rarely consumed crops. Individual estimates of crop consumption were positively correlated with the proportion of GPS-collar locations in crop fields. Females, but not males, decreased crop consumption in years with high availability of natural fall foods. Further, the degree of crop consumption was more closely tied to local crop availability and landscape composition in females than in males. Weight and fat were positively correlated with crop use for both sexes, and males’ use of crops also increased with their physical stature, suggesting that crops provided substantial caloric benefits to bears and that social dominance may have influenced foraging decisions. However, a large segment of this bear population (44% of sampled bear–years) made little use of crops, and crops accounted for more than half the fall diet for only 14% of the population. Whereas some bears clearly benefited from consumption of crops, we conclude that a population of bears could be sustained in this largely agricultural region even without crops as a food source.

EPS05.2 Novel point of care immobilized lipase device (EFIC™) is compatible with a range of nutritional formulas and can simplify delivery of hydrolyzed fat during tube feeding

Objectives Enteral feeding is widely used to improve nutritional status in people with developmental immaturity or exocrine pancreatic insufficiency (EPI) including CF. While all fats provide caloric benefit, long-chain polyunsaturated fatty acids (LCPUFA) are also structural components of membranes and biological mediators involved in the regulation of many physiological functions. However use of PERTs is ineffective with liquid formula in particular LCPUFA digestion. Alcresta has developed the Enteral Feeding In-Line Cartridge (EFIC), a single-use point-of-care device containing immobilized lipase. A microbial lipase was selected based on its ability to hydrolyze LCPUFAs since these are the most complex fats to digest and the fatty acids most deficient in EPI. Enteral formula passes through the EFIC ex-vivo resulting in rapid hydrolysis of fats into readily absorbable fatty acids and monoglycerides. Methods A colorimetric assay (detection: C8 to C20) was used to measure fatty acid release resulting from the action of the EFIC. A range of commercially available enteral formulas was tested. The EFIC device was evaluated in terms of the percent of hydrolyzed fat delivered over the length of the feeding. Results Overall, for most commercial formulas the EFIC hydrolyzes ∼90% of fat, in particular physiologically relevant LCPUFA such as DHA, EPA and AA while leaving other nutritional components and flow rate unaffected. Conclusion This novel EFIC device consistently optimizes delivery of readily absorbable fats to patients with compromised pancreatic function using enteral feeding (e.g. premature infants, cystic fibrosis or oncology).

Skecher Shape-ups Do Not Increase the Metabolic Cost of Walking

BACKGROUND: Skecher Shape-Ups (SSU) are advertised as an enhancer of the effect of physical activity (i.e., metabolic cost) and therefore increase the efficiency of time spent ambulating. PURPOSE: To determine if wearing SSU increases the metabolic cost of walking. Furthermore, we sought to determine if weight differences between shod conditions accounted for any metabolic changes. METHODS: Twenty-eight subjects (17 females, 11 males; age = 22.8 ± 6.6 y; mass = 72.4 ± 20.2 kg; height = 170.0 ± 6.7 cm; % fat = 23.0 ± 11.7 %) walked on a treadmill (0% grade) at a self-selected speed plus 10% (76.1 ± 11.8 m·min-1) in each of the following lab-provided shoes: SSU, walking regular shoe (W), and walking in regular shoe plus the difference between SSU and W shoe mass (WM). There was about 2-5 minutes rest between randomized conditions for subjects to change shoes and/or have weight added to the shoe. Accumulated breath-by-breath VO2 was measured for 10 minutes during each condition (ORCA Cardiopulmonary System, Santa Barbara, CA). VO2 mode was determined from 10 minutes of data for each condition and a repeated-measures ANOVA was used to compareVO2 mode among shod conditions (p < 0.05). RESULTS: There was no significant difference in VO2 among walking shoe conditions (9.9 ± 3.1, 9.8 ± 3.4, & 10.2 ± 3.0 mlO2·kg-1·min-1 for SSU, W, & WM, respectively; p = 0.068). CONCLUSION: SSU and WM did not increase the metabolic cost of exercise (VO2) for healthy, young subjects walking slightly faster than a preferred speed. It seems that there is no additional caloric benefit of wearing SSU beyond the typical walking shoe.

Honey bee forager thoracic temperature inside the nest is tuned to broad-scale differences in recruitment motivation

Insects that regulate flight muscle temperatures serve as crucial pollinators in a broad range of ecosystems, in part because they forage over a wide span of temperatures. Honey bees are a classic example and maintain their thoracic muscles at temperatures (T(th)) tuned to the caloric benefits of floral resources. Using infrared thermography, we tested the hypothesis that forager motivation to recruit nestmates for a food source is positively correlated with T(th). We trained bees to a sucrose feeder located 5-100 m from the nest. Recruiting foragers had a significantly higher average T(th) (2.7°C higher) when returning from 2.5 mol l(-1) sucrose (65% w/w) than when returning from 1.0 mol l(-1) sucrose (31% w/w). Foragers exhibited significantly larger thermal fluctuations the longer they spent inside the nest between foraging trips. The difference between maximum and minimum temperatures during a nest visit (T(range)) increased with total duration of the nest visit (0.7°C increase per additional min spent inside the nest). Bees that recruited nestmates (waggle or round danced) were significantly warmer, with a 1.4-1.5 times higher ΔT(th) (difference between T(th) and nest ambient air temperature) than bees who tremble danced or simply walked on the nest floor without recruiting between foraging bouts. However, recruiter T(th) was not correlated with finer-scale measures of motivation: the number of waggle dance circuits or waggle dance return phase duration. These results support the hypothesis that forager T(th) within the nest is correlated to broad-scale differences in foraging motivation.

The meat-scrap hypothesis: small quantities of meat may promote cooperative hunting in wild chimpanzees (Pan troglodytes)

A common explanation for hunting in groups is that doing so yields a greater per capita caloric benefit than hunting solitarily. This is logical for social carnivores, which rely exclusively on meat for energy, but arguably not for omnivores, which obtain calories from either plant or animal matter. The common chimpanzee, Pan troglodytes, is one of the few true omnivores that regularly hunts in groups. Studies to date have yielded conflicting data regarding the payoffs of group hunting in chimpanzees. Here, we interpret chimpanzee hunting patterns using a new approach. In contrast to the classical assumption that hunting with others maximizes per capita caloric intake, we propose that group hunting is favored because it maximizes an individual’s likelihood of obtaining important micronutrients that may be found in small quantities of meat. We describe a mathematical model demonstrating that group hunting may evolve when individuals can obtain micronutrients more frequently by hunting in groups than by hunting solitarily, provided that group size is below a certain threshold. Twenty five years of data from Gombe National Park, Tanzania are consistent with this prediction. We propose that our ‘meat-scrap’ hypothesis is a unifying approach that may explain group hunting by chimpanzees and other social omnivores.

The Role of Basketry in Early Holocene Small Seed Exploitation: Implications of a Ca. 9,000 Year-Old Basket from Cowboy Cave, Utah

Despite ranking at the low end of the continuum in net caloric benefit relative to other foods, small seeds assumed great dietary importance in many parts of the world, including western North America. In a series of publications, Adovasio (1970a, 1974, 1980, 1986) argued that coiled basketry technology was invented in the eastern Great Basin during the early Holocene as a specialized food-processing technique. Coiled baskets are indeed useful for collecting and processing seeds, but it does not necessarily follow that they were originally designed for this purpose. A whole basket recently discovered at Cowboy Cave in southeastern Utah returned an AMS radiocarbon assay of 7960 ± 50 B.P., making it currently the earliest directly dated coiled basket from the Americas. This basket is not a parching tray and likely had nothing to do with harvesting seeds. We discuss the implications of this find with regard to tracking the temporal spread of coiled basketry technology in western North America and the role of coiled and twined forms in the initiation of small seed exploitation. Coiled and twined baskets for small seed processing may result from reconfiguration of existing technologies to create novel forms suited to a new food exploitation strategy.

Modulation of the ubiquitin-proteasome proteolytic pathway by eicosapentaenoic acid supplementation in a model of progressive malignancy.

A benefit for eicosapentaenoic acid (EPA) supplementation for protein maintenance in cancer patients exists, although specific mechanisms are unknown. As the ubiquitin-proteasome proteolytic (UPP) pathway has been implicated in protein use in malignancy, we determined mRNA levels for UPP components in the liver and muscles from EPA-treated rats bearing the methylcholanthrene (MCA) fibrosarcoma. Rats implanted with MCA tumor were divided into 3 groups on day 13: EPA (5 g/kg per day plus 10 IU vitamin E/g fat), corn oil (5 g/kg per day plus 10 IU vitamin E/g fat), and saline (5 g/kg per day plus 10 IU E/g saline). On day 29, tumor volume (TV) was determined; liver and quadriceps muscles were also excised to determine gene expression of C2, C3, E2(14k), and E3alpha by reverse transcription-polymerase chain reaction (RT-PCR). EPA-treated rats demonstrated a reduced TV of 21% compared with the 28% and 30% TV of corn oil- and saline-treated rats, respectively. Muscle mRNA levels of E2(14k) and E3alpha in EPA-treated animals were decreased compared with corn oil- and saline-treated animals. EPA treatment also decreased hepatic C2, C3, and E2(14k) mRNA levels compared with saline treatment. EPA supplement decreased skeletal muscle E2(14k), E3alpha, and hepatic C2 mRNA levels compared with the isocaloric, isonitrogenous corn oil supplement, supporting a treatment-specific effect. The decrease in hepatic C3 and E2(14k) mRNA levels induced by EPA were partly because of caloric benefit and partly attributable to a treatment-specific effect. Additionally, differences in the hepatic and muscle gene expressions of UPP components suggested an organ-specific effect for omega-3 fatty acid activity.

Fermenting fruit and the historical ecology of ethanol ingestion: is alcoholism in modern humans an evolutionary hangover?

In the field of addiction research, the possibility of ancestral exposure to psychoactive compounds has generally been excluded. A paleobiological approach to the human diet, however, illustrates the potential utility of historical data in interpreting modern-day addictive behaviors. Low-level dietary exposure to ethanol via ingestion of fermenting fruit has probably characterized the predominantly frugivorous anthropoid lineage for about 40 million years. Potentially adaptive primate behaviors associated with the natural occurrence of ethanol include the olfactory use of ethanol plumes to localize fruit crops, the use of ethanol as an appetitive stimulant to facilitate rapid consumption of transient nutritional resources, and the physiological exploitation of the caloric benefits of ethanol. Such behavioral and energetic advantages probably pertain to all animal taxa that consume fermenting fruit, and may have been retained in modern humans in spite of considerable dietary diversification over the last several million years. In contemporary human environments, excessive consumption of ethanol would then represent maladaptive cooption of ancestrally advantageous behaviors given essentially ad libitum access to a compound otherwise found only within scarce nutritional substrates. Epidemiologically demonstrated health benefits of low-level alcohol consumption are consistent with an ancient and potentially adaptive exposure of primate frugivores to this most common of the psychoactive substances.

The role of aquatic moss on community composition and drift of fish-food organisms

Macroinvertebrate density, biomass and drift were studied from moss-covered and moss-free channels in the South Fork Salmon River, Idaho. Insect densities were compared for 10 different substrate types and locations involving moss (Fontinalis neo-mexicana), sand, pebbles and cobbles. An ANOVA test demonstrated that insect densities varied significantly with substrate type (P < 0.05), and that total insect density in moss clumps differed significantly from densities in mineral substrates. Insect densities were 4–18 times greater in moss clumps than in mineral substrates under and adjacent to moss; sands under moss supported the lowest densities. During most tests, densities in pebble and cobble substrates adjacent to moss clumps were not significantly different from those found in similar substrates in the moss-free channel. The 20% moss-covered channel had 1.6 to 7.2 greater insect density and 1.4 to 6.1 greater biomass than did the moss-free channel for the tests conducted. Generally, midges (Chironomidae) made up over 50% of the insect community; annelids were the principal non-insect invertebrates. In spite of greater insect density and biomass in a moss-covered than in the moss-free channel, we did not demonstrate universally increased drift of the immature stages from the moss-covered channel, at least during daylight hours. As a consequence, we infer that salmonid fishes, feeding primarily on drifting insects during the daytime, may not derive increased caloric benefit from moss habitats until the insects emerge as adults.

Conditioned taste preferences based on caloric density.

Conditioning involved adding one flavor (e.g., vanilla) to an artificial diet of high caloric density and a second flavor (e.g., anise) to a similar low-calorie diet. When the rats were tested with identical foods to which the flavors were added, they showed a strong preference for the high-calorie flavor. The parameters of conditioning were varied in four experiments, which showed that the conditioning of taste preferences is rapid and powerful and has generality over a range of conditioned stimulus parameters. The last experiment indicated that the unconditioned stimulus for this conditioning is probably some oral cue, such as the taste of starch, which is correlated with caloric benefit, rather than caloric benefit per se.

Foraging Strategies and Energetics of East African Sunbirds at Mistletoe Flowers

Sunbirds (Nectariniidae) feeding on nectar of the mistletoe, Phragmanthera dshallensis, in central Kenya encounter two types of flowers. Closed flowers, which have not been visited previously and must be opened by the feeding bird, contain more nectar and require more feeding time than open flowers. Open flowers result from the visitation and explosive opening of closed flowers. Closed flowers are rarer overall than open flowers, although occasionally a local area may have a majority of closed flowers. The different-sized sunbird species tend to take different proportions of open and closed flowers; generally there is a positive relation between bird size and percentage of closed flowers taken. We examined benefits and costs for each bird species feeding in local patches of mistletoe. The benefits were the same for each species. The time costs varied inversely with bird size. These differences were reduced by the lower energetic costs of the smaller species. For all species the caloric benefit to cost ratio (= foraging efficiency) increased with increasing proportions of closed flowers visited. However the foraging efficiency difference between 0% and 100% closed flowers was greatest for kilimensis, indicating that kilimensis gained more by preferentially moving to patches with high proportions of closed flowers. The data on percentage closed flowers actually taken indicate that those species which should derive greater energy benefits by taking higher proportions of closed flowers tend to do so. Complete specialization on closed flowers, however, apparently is prevented by increasing search costs within and between patches. The sunbird foraging behavior is consistent with predictions based on maximizing foraging efficiencies as a function of relative energy value of the two flower types.