Genetics, archaeology, and holocene hunter-gatherers

Diets of modern hunter-gatherers vary substantially in their carbohydrate content depending on ecoenvironments: results from an ethnographic analysis

In the past, attempts have been made to estimate the carbohydrate contents of preagricultural human diets. Those estimations have primarily been based on interpretations of ethnographic data of modern hunter-gatherers. In this study, it was hypothesized that diets of modern hunter-gatherers vary in their carbohydrate content depending on ecoenvironments. Thus, using data of plant-to-animal subsistence ratios, we calculated the carbohydrate intake (percentage of the total energy) in 229 hunter-gatherer diets throughout the world and determined how differences in ecological environments altered carbohydrate intake. We found a wide range of carbohydrate intake (≈3%-50% of the total energy intake; median and mode, 16%-22% of the total energy). Hunter-gatherer diets were characterized by an identical carbohydrate intake (30%-35% of the total energy) over a wide range of latitude intervals (11°-40° north or south of the equator). However, with increasing latitude intervals from 41° to greater than 60°, carbohydrate intake decreased markedly from approximately equal to 20% to 9% or less of the total energy. Hunter-gatherers living in desert and tropical grasslands consumed the most carbohydrates (≈29%-34% of the total energy). Diets of hunter-gatherers living in northern areas (tundra and northern coniferous forest) contained a very low carbohydrate content (≤15% of the total energy). In conclusion, diets of hunter-gatherers showed substantial variation in their carbohydrate content. Independent of the local environment, however, the range of energy intake from carbohydrates in the diets of most hunter-gatherer societies was markedly different (lower) from the amounts currently recommended for healthy humans.

Latitude, local ecology, and hunter-gatherer dietary acid load: implications from evolutionary ecology

BACKGROUND

Past estimations of the net base-producing nature of the Paleolithic "Diet of Evolutionary Adaptedness" derived primarily from interpretations of ethnographic data of modern historically studied hunter-gatherers. In our recent ethnographic analyses, we observed large variations in diet-dependent net endogenous acid production (NEAP) among hunter-gatherer diets.

OBJECTIVE

We proposed to determine whether differences in ecologic environments influence estimations of NEAP.

DESIGN

By using ethnographic data of plant-to-animal subsistence ratios and mathematical models established previously, we computed frequency distributions of estimated NEAP in relation to latitude in 229 worldwide modern hunter-gatherer societies. Four different models of animal fat density were used: models A (3%), B (10%), C (15%), and D (20%). In addition, we estimated NEAP by primary ecologic environments in those hunter-gatherer societies (n = 63) for which data were documented.

RESULTS

With increasing latitude intervals, 0°-10° to >60°, NEAP increased in all 4 models. For models A, B, and C, the diets tend to be net acid-producing at >40° latitude and net base-producing at <40°; the same held for model D (>50° and <50°, respectively). For models A, B, and C, the diets of hunter-gatherers living in northern areas (tundra and coniforest) and in temperate grassland and tropical rainforests are net acid-producing. In all other ecologic niches, hunter-gatherers seem to consume a neutral or net base-producing diet.

CONCLUSIONS

Latitude and ecologic environments codetermine the NEAP values observed in modern hunter-gatherers. The data support the hypothesis that the diet of Homo sapiens' East African ancestors was predominantly net base-producing.

Estimation of the diet-dependent net acid load in 229 worldwide historically studied hunter-gatherer societies

BACKGROUND

Nutrition scientists are showing growing interest in the diet patterns of preagricultural (hunter-gatherer) humans. Retrojected preagricultural diets are reportedly predominantly net base producing in contrast to the net acid-producing modern Western diets.

OBJECTIVE

We examined the dietary net acid load [net endogenous acid production (NEAP)] for 229 worldwide historically studied hunter-gatherer societies to determine how differences in plant-to-animal (P:A) dietary subsistence patterns and differences in the percentage of body fat in prey animals affect the NEAP.

DESIGN

With the use of 1) ethnographic data of dietary P:A ratios of hunter-gatherer populations, 2) established computational methods, and 3) knowledge that fat densities of animal foods consumed by hunter-gatherers varied between 3% and 20%, we computed the NEAP for the diets of 229 populations in 4 different models of animal fat densities (model A, 3%; model B, 10%; model C, 15%; model D, 20%).

RESULTS

As P:A ratios decreased from 85:15 to 5:95, the NEAP increased from -178 to +181 mEq/d (model A) and from -185 to +120 mEq/d (models B and C). Approximately 50% of the diets consumed by the 229 worldwide hunter-gatherer populations were net acid producing (models B and C). In model D, 40% of the diets were net acid producing.

CONCLUSIONS

Our data confirm that the NEAP of hunter-gatherer diets becomes progressively more positive as P:A ratios decline. The high reliance on animal-based foods of a worldwide sample of historically studied hunter-gatherer populations renders their diets net acid producing in approximately 40-60% of subgroups of P:A ratios. Only further investigations can show the implications of these findings in determining the NEAP of human ancestral diets.

Mitochondria make a come back

This review attempts to summarize our present state of knowledge of mitochondria in relation to a number of areas of biology, and to indicate where future research might be directed. In the evolution of eukaryotic cells mitochondria have for a long time played a prominent role. Nowadays their integration into many activities of a cell, and their dynamic behavior as subcellular organelles within a cell and during cell division are a major focus of attention. The crystal structures of the major complexes of the electron transport chain (except complex I) have been established, permitting increasingly detailed analyses of the important mechanism of proton pumping coupled to electron transport. The mitochondrial genome and its replication and expression are beginning to be understood in considerable detail, but more questions remain with regard to mutations and their repair, and the segregation of the mtDNA in oogenesis and development. Much emphasis and a large effort have recently been devoted to understand the role of mitochondria in programmed cell death (apoptosis). The understanding of their central role in mitochondrial diseases is a major achievement of the past decade. Finally, various drugs have traditionally played a part in understanding biochemical mechanisms within mitochondria; the repertoire of drugs with novel and interesting targets is expanding.