The Role Of Milk In Human Evolution

It has been suggested that lactation evolved as the most advantageous way to provide infant nutrition when food was unavailable or patchy, despite inefficiencies associated with converting nutrients from food to reserves and milk (14). One of the best nutrient-related examples of human genetic variation maintained via natural selection is given by our ability to digest milk lactose. Like most mammals, humans slowly lose their ability to digest lactose after weaning and have a low digestive...

Vitamin D

Calcitriol (vitamin D3 ) is the active form of vitamin D and elicits an effect on gene transcription via the vitamin D receptor (VDR), which forms a heterodimer with the RXR (retinoid-X receptor). Thus, vitamins A and D work in concert for many genomic-functions of vitamin D. Polymorphisms of the VDR (Figure 3.7) may act by a similar gene-nutrient interaction to that of the MTHFR SNP in respect to the etiology of human disease (25) Vitamin D3 is thought to protect against breast cancer. VDR...

Brief History Of The Human Diet

Early man met his needs for macro- and micronutrients via a largely herbivorous diet (12). It has been postulated that as man moved toward a more nutrient-dense diet, this facilitated an increase in brain dimension with a concomitant decrease in gut size (13). Such a diet was likely to contain not just animal fat and protein but plants (leaves shoots roots berries). Clearly, a significant mismatch exists between our ancestral diet and our contemporary one, which is energy rich-nutrient poor....

Phytoestrogens and Reproduction

Whether phytoestrogens found in many plant foods have played any role in reproductive success at a level that may have evolutionary implications is unclear. However, these isoflavones compete with endogenous estrogens such as estradiol for occupancy of the estrogen receptor (ER), which is common to many reproductive tissues. The bound ligand is responsible for activation of the genomic estrogen response element within the nucleus and, hence, protein expression. An excessive stimulation of ERs...

A small and very old lady from Flores provides human evolutionary biologists with a dilemma

In late 2004, the unearthing of an 18,000-year-old skeleton at Liang Bua on the Eastern Indonesian island of Flores has presented a significant paradox for evolutionary biologists to ponder si, S2. The discovery of tiny, 1-m-tall hominins, nicknamed hobbits by their discoverers, but more correctly termed Homo floriensis brought to the worlds attention a species with a brain roughly one third the size of that of modern man's. However, despite such a small brain, it seems that this new species of...

Population Genetics and the Hardy Weinberg Equilibrium

If we want to examine allelic frequency within a population, and the forces that impact upon and change either the frequency of gene alleles or the genotypes, we can. The Hardy-Weinberg equilibrium permits us to calculate the expected genotype frequency from the allele frequency within the same population and the allele frequency from the known genotype. To accomplish this, we make certain assumptions Mating occurs at random reproductive efficiency is constant no mutations are occurring there...

Contemporary Dietary Patterns that Work The Mediterranean Diet

There is little doubt that at a broad level, today's consumers are far more aware of the important relationship between diet and disease than ever before. It is popular knowledge that, for example, the Mediterranean diet is beneficial, whereas a diet of pie and chips washed down with a pint of beer is not. What is it about the Mediterranean diet, for example, that affords protection against cardiovascular disease and cancer (174 -176) Much research today is focused on specific food items of...

Zinc Manganese Magnesium Iron and Copper

Zinc has a wide range of effects within a panoply of dependent proteins, many of which are tasked with maintaining replication and the normal functioning of DNA. Examples include zinc finger proteins, which act as important transcription factors. Zinc is present at vastly elevated levels in seminal fluid compared with blood plasma. This implies a critical role for zinc in spermatogenesis and spermatozoal stability (84). Low zinc levels are found in infertile males and are associated with...

Advantage of the Alanine Glyoxylate Aminotransferase AGT Pro11Leu Polymorphism in Meat Eaters

AGT is an important enzyme in intermediary metabolism. A C-to-T substitution in the AGT gene leads to the Pro11Leu polymorphism, which causes a three-fold decrease in enzyme activity along with a small amount of protein mistargeted between organelles. The effect of this on the synthesis and excretion of oxalate and deposition of calcium oxalate crystals in the kidney and urinary tract is thought to be significant. It has been postulated that there is a distinct advantage to possession of this...

Info

A dHPLC designed for the detection of new and potentially interesting SNPs in candidate genes. Figure 13.1. A dHPLC designed for the detection of new and potentially interesting SNPs in candidate genes. This technique has been used to sequence entire genomes that are billions of base pairs long, albeit in bite-sized portions around 500 base pairs in length. 13.3 NUCLEIC ACID MICROCHIP TECHNIQUES Nucleic acid microchips permit the analysis of thousands of genes simultaneously and in...

Vitamin A

Retinoic acid (RA) interacts with receptors in the nucleus. RA binds to steroid and thyroid hormone receptors, which are a family of ligand-sensitive transcription factors. All-trans RA binds to the RA receptor (RAR), whereas 9-cis RA binds to the retinoid-X receptor (RXR). The binding of the heterodimer RAR RXR to a specific retinoic acid response element (RARE) on DNA regulates gene transcription (Figure 3.3). Vitamin A is probably best known for its role in vision (Figure 2.10) however, most...

Possible Evolutionary Impact

The generic term lecithin is used mainly when referring to the body's major phospolipid phosphatidylcholine. However, it is often used to embrace the four related, major categories of phospholipid. These are phosphatidylcholine, phosphatidylserine, phos-phatidylethanolamine, and phosphatidylinositol. The structure is given for these phospho-lipids in Figure 9.1. The parent generic structure comprises two fatty acid chains esterified to a glycerol moiety, a phosphate group, and a basic...

Evolution Of Xenobiotic Metabolism In Humans

Xenobiotics Metabolism Liver

Xenobiotics are foreign chemicals that are not a normal component of the organism that is exposed to them. This includes most drugs and many plant phytochemicals that are alien to human metabolism, but that were nonetheless a part of our ancestral diet. Humans have acquired the capability to avoid an accumulation of harmful dietary xenobiotics within cells as well as the ability to eliminate them from our bodies. To achieve this, multiple xenobiotic metabolizing enzymes with differential, but...

Mechanisms of Folate as an Evolutionary Pressure on Gametogenesis

In the context of nutrigenomics and gametogenesis, 5,10-methylenetetrahydrofolate and its dependent polymorphic enzyme 5,10-methylenetetrahydrofolate reductase (5,10MTHFR) are crucial intermediates in folate metabolism Although 5,10-methylenetetrahydrofolate is used by the reductase to produce 5-methyltetrahydrofolate and de novo methionine (Figure 2.8), it is also required by both thymidylate synthase and methylenetetrahydro-folate dehydrogenase in the synthesis of DNA-thymine and purine,...

Thirsty Genes Putative Thrifty Genes that May Have Been Selected to Counter Water Stress but Now Lead to Hypertension

Humans have a physiological requirement for salt and mineral sodium. Indeed, one of our most basic senses of taste is for saltiness. This taste is not unpleasant, and it is perhaps unsurprising that in the West, our salt intake far exceeds our physiologic needs. Even the U.S. Food and Drug Administration recommendation of 6 g day for a low-salt diet is estimated to be 3.5x that of the typical Paleolithic diet. Some people are sensitive to salt and possess a genetic predisposition toward...

The Omics Revolution

The new technologies that embrace the term -omics have evolved to address increasingly complex biological questions arising out of the postgenomics era. I describe some of these advanced techniques toward the end of this book. Briefly they encompass techniques like DNA microarray technology, real-time polymerase chain reaction, denaturing hplc, two-dimensional (2-D) protein electrophoresis coupled with matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry, and...

The Evolution of Human Disease

7.1 THE CONFLICT BETWEEN AGRICULTURE AND ANCESTRAL GENES This section examines how an increase in brain size has led to our meteoric success as a species, but in the process, it has led to a modern lifestyle that is not compatible with our ancestral genes. Human genetic change does occur, but it is slow. Before examining this issue in depth, it is worth mentioning what I believe is one of the most interesting examples of molecular evolution illustrative of a positive selection pressure in...

Chemical Structure Of Food Toxins

Structure Fugu Fish Poison

Preformed vitamin A (not carotenoid derived provitamin A) has a spectrum of effects that in extreme cases (i.e., too much or too little) can lead to death. In particular, excess vitamin A derived from polar bear or oily fish livers has been associated with serious clinical conditions. Figure 10.1. Preformed vitamin A (not carotenoid derived provitamin A) has a spectrum of effects that in extreme cases (i.e., too much or too little) can lead to death. In particular, excess vitamin A...

The Evolution of Micronutrient Metabolism

5.1 ANTIOXIDANTS, EVOLUTION, AND HUMAN HEALTH One of the great biological paradoxes is that although oxygen is vital for much planetary life, it can also cause great damage to our delicate cellular mechanisms. Antioxidant mechanisms therefore evolved to cope with the rise of an oxygen-rich atmosphere (Figure 5.1). A diet rich in plant antioxidants augments our inherent defense strategies for reactive oxygen species (ROS) i.e., our cellular biology interacts with the external environment to...

Human Encephalisation May Be Linked To An Evolutionary Reduction In Gut Mass

Humans are unusual in that they have a larger brain size than might be predicted based on their body size. Such dramatic encephalization has only occurred in the last 2-3 million years, with a three-fold increase in brain size since the time of Australopithecus aferensis (the Lucy skeleton) 4.5 million years ago (91). To permit this degree of encephalization, two requirements must have been met (1) adequate supply of polyunsaturated fatty acids, in particular, arachidonic and docosahexaenoic...

The Cost Benefit Analysis of Polymorphisms within Lipoprotein Metabolism

Mthfr C677t Gene Polymorphism

Apolipoprotein E is central to blood lipoprotein homeostasis and lipid transport within tissues. The gene (APO-E) encoding this protein is polymorphic. Although the APO-E4 allele is a well-established risk factor for both vascular disease and Alzheimer's disease in Figure 2.8. Schematic showing the MTHFR locus, which is encoded by a variant C677T-MTHFR gene. The implication of the genetic selection of the MTHFR genotype, folate metabolism, and reproductive efficiency is dealt with in an...

Nutrigenomics

I provided a definition of nutritional genetics and nutrigenomics earlier. Most of the information detailed in this book is hung on a framework of one or the other of these important areas. However, although my theme throughout this book has been on the role of nutrition in human evolution, scientists around the world have tackled these important areas largely to help understand and attenuate human disease and suffering. Muller and Kersten 198 describe nutrigenomics as the application of...

Micronutrients And The Evolution Of Skin Pigmentation

Two key micronutrients may have played a critical role in the evolution of skin coloration. Pigmentation with melanin is an adaptive response that is maintained by natural selection. The vitamin D hypothesis states that pale skins were necessary outside tropical latitudes to facilitate vitamin D biosynthesis within the skin from low levels of UV light. Thus, depigmentation evolved as humankind radiated out of the tropics where a dark skin protected against excess, even toxic, synthesis of...

Antioxidant Micronutrients Vitamins E C carotene and Selenium

A deficiency in these important antioxidant nutrients will cause chromosomal damage and oxidative lesions to membrane structures. Outside of its crucial role as a coenzyme for copper-dependent hydroxylases and a-ketoglutarate-linked iron-containing hydroxylases, vitamin C has generalized antioxidant properties, including salvage of the spent tocopheroxyl radical back to a -tocopherol vitamin E . Vitamin C can neutralize reactive oxygen species ROS and, hence, protect nuclear and membrane...

The Evolution Of Taste As A Survival Mechanism

The ability to taste and smell allows us to interact much more efficiently with our environment, and in the context of taste in particular, influences our choice of foods. Human taste can be broken down into five categories salty, sour, sweet, umami, and bitter 73,74 . The molecular basis of taste is similar to both smell and sight see Figure 2.11. It seems likely that the bitter modality may be especially important because it can alert us to many phytotoxins that tend to have a bitter taste....

Iron as a Recent Evolutionary Pressure on Reproductive Fecundity

Early European populations are likely to have suffered from iron deficiency and consequently an increase in premature delivery and hence low birth-weight offspring 44,45 . It has been demonstrated that hemochromatosis, a genetic disease associated with progressive iron overload, is associated with a C282Y mutation in the HLA-H gene. This gene has reached a high frequency in a short time it arose around 60 generations ago 46,47 . This positive selection may well have improved the reproductive...