what is human biological variation

Human variability, or human variation, is the range of possible values for any characteristic, physical or mental, of human beings. Frequently debated areas of variability include cognitive ability, personality, physical appearance and immunology. Variability is partly heritable and partly acquired. As the human species exhibits sexual dimorphism, many traits show significant variation not just between populations but also between the sexes.

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What is human genetic variation?

Human genetic variation is the genetic differences in and among populations. There may be multiple variants of any given gene in the human population ( alleles ), a situation called polymorphism .

What are the areas of study of human biological variation?

Human biological variation. The major areas of study of human biological variation are growth and development, genetic variation ( Fig. 1 ), variation related to climate, infectious and noninfectious diseases, and demography. Modern anthropologists and human biologists appreciate the essentially adaptive nature of human variability and...

What is meant by biological variation?

Biological Variation Biological variation refers to the variance in test results within a single individual over a specified period of time, and between individuals of a defined population. From: Clinical Biochemistry, 2013

How much variation is there in the human species?

Genetic studies demonstrate that about 85.4 percent of all the variation in the human species can be attributed to variation within populations and that there is only a 6.3 percent difference between “races,” with less than half of this value accounted for by known racial groupings (see Lewontin 1972; Barbujani, Magani, Minch, et al. 1997).

What is meant by biological variation?

Biological variation or variance can be defined as the appearance of differences in the magnitude of response among individuals in the same population given the same dose of a compound.

What is an example of biological variation?

Eye colour, body form, and disease resistance are genotypic variations. Individuals with multiple sets of chromosomes are called polyploid; many common plants have two or more times the normal number of chromosomes, and new species may arise by this type of variation.

What is the source of human biological variation?

Such groups already have a wide and complex range of hereditary physical characteristics; indeed, human hereditary variability is a product of human sexual reproduction, whereby every individual receives half of his or her genetic endowment from each parent and no two individuals (except for identical twins) inherit ...

What is human biological variation in anthropology?

The diversity of biological and genetic differences observed in the human population.

Why is biological variation important?

Biological variation is essential to species survival because natural selection acts upon the phenotypic variation within a population: the more varied the population's genetic resources, the more likely that the population will persist into the future.

What are some common human variations?

Common human variationsType of VariationExampleSkin ColorHuman skin color AlbinismEye ColorEye color Martin scaleHair ColorHuman hair color Hair coloringHair QuantityHair loss Hirsutism4 more rows

What are the importance of variation in human being?

Using the ability to reproduce, living organisms increase their population and feed on available resources in their niche. Changes in DNA and body design may result in difficulty to sustain themselves in their habitat.

Do humans vary biologically?

Between any two humans, the amount of genetic variation—biochemical individuality—is about . 1 percent. This means that about one base pair out of every 1,000 will be different between any two individuals.

What are types of variation?

More examplesContinuous variationDiscontinuous variationHeightBlood groupWeightHand used to write withArm spanEye colourHead circumference at birthAbility to roll tongue

How can biological anthropologists understand human biological variation?

How can physical anthropologists understand human biological variation? They can investigate genes, as they are the primary determinant of human variation. They can study health, as most human variation is the result of health differences.

Why do anthropologists study human variation and how do they explain it?

Such investigation can give us clues as to how unique we are as a biological organism in relation to the rest of the animal kingdom. Second, anthropologists study modern human diversity to understand how different biological traits developed over evolutionary time.

What is an example of biological anthropology?

For example, biological anthropologists often look at the biology of human remains, including past diets and the prevalence of ancient diseases. Fossils, bones, and other remains provide enormous clues regarding the lives of ancient peoples and how they interacted with their environments.

What are the types of variation in biology?

More examplesContinuous variationDiscontinuous variationHeightBlood groupWeightHand used to write withArm spanEye colourHead circumference at birthAbility to roll tongue

What is biological variation in nursing?

Biological Variation These factors include race, body structure, genetic variations, nutritional preferences and psychological characteristics (Davidhizar, & Giger, 2008). Nursing examples include diseases related to specific ethnic groups as well as rural versus urban health.

Which of the following is an example of genetic variation?

Answer. Answer: examples of genetic variation include eye colour ,blood type ,camouflage in animals and leaf modification in plants.

What is within subject biological variation?

Background: Within-subject biological variation data (CVI) are used to establish quality requirements for assays and allow calculation of the reference change value (RCV) for quantitative clinical laboratory tests.

Why do anthropologists study human biology?

Anthropologists study human biology to better understand the extent of human biological variability, to explain the mechanisms that create and pattern this variability, to relate variability to health and disease, and to understand the sociocultural factors ...

What are the areas of study of human variation?

The major areas of study of human biological variation are growth and development, genetic variation ( Fig. 1 ), variation related to climate, infectious and noninfectious diseases, and demography. Modern anthropologists and human biologists appreciate the essentially adaptive nature of human variability and the importance of the concept ...

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AccessScience provides the most accurate and trustworthy scientific information available. Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students.

How did people with light skin color evolve?

Peoples with light skin colours evolved over thousands of years in northern temperate climates. Human groups intermittently migrating into Europe and the northern parts of the Eurasian landmass over the past 25,000–50,000 years experienced a gradual loss of skin pigmentation. The changes were both physiological and genetic; that is, there were systemic changes in individuals and long-range genetic changes as a result of natural selection and, possibly, mutations. Those individuals with the lightest skin colours, with lowest amounts of melanin, survived and reproduced in larger numbers and thus passed on their genes for lighter skin. Over time, entire populations living in northern climates evolved lighter skin tones than those individuals living in areas with higher levels of sunlight. Between populations with light skin and those with the darkest coloration are populations with various shades of light tan to brown. The cline in skin colours shows variation by infinite degrees; any attempts to place boundaries along this cline represent purely arbitrary decisions.

Why is dark skin darker than light skin?

Scientists at the turn of the 21st century understood why these superficial visible differences developed. Melanin, a substance that makes the skin dark, has been shown to confer protection from sunburn and skin cancers in those very areas where ultraviolet sunlight is strongest. Dark skin, which tends to be thicker than light skin, may have other protective functions in tropical environments where biting insects and other vectors of disease are constant threats to human survival. But humans also need vitamin D, which is synthesized by sunlight from sterols (chemical compounds) present in the skin. Vitamin D affects bone growth, and, without a sufficient amount, the disease known as rickets would have been devastating to early human groups trying to survive in the cold, wintry weather of the north. As these groups adapted to northern climates with limited sunlight, natural selection brought about the gradual loss of melanin in favour of skin tones that enabled some individuals to better synthesize vitamin D.

How do scientists understand human variability?

In the last decades of the 20th century, scientists began to understand human physical variability in clinal terms and to recognize that it reflects much more complex gradations and combinations than they had anticipated. To comprehend the full expression of a feature’s genetic variability, it must be studied separately over geographic space and often in terms of its adaptive value. Many features are now known to relate to the environmental conditions of the populations that carry them.

What are some examples of adaptation?

The global distribution of skin colour ( see map) is the best example of adaptation, and the consequences of this process have long been well known. Skin colour clines (gradations) in indigenous populations worldwide correlate with latitude and amounts of sunlight. Indigenous populations within a broad band known as the tropics (the regions falling in latitude between the Tropics of Cancer and Capricorn) have darker skin colours than indigenous populations outside of these regions.

How do adaptive variations affect the body?

Many peoples adapted to cold climates, for example, have protective physiological reactions in their blood supply. Their blood vessels either constrict the flow to extremities to keep the inner body warm while their surface skin may be very cold (vasoconstriction) or dilate to increase the blood flow to the hands, feet, and head to warm the outer surfaces (vasodilation).

What are some examples of human genetic variation?

The prevalence of diseases has been another major factor in the evolution of human diversity, and some of the most important of human genetic variations reflect differences in immunities to diseases. The sickle cell trait ( hemoglobin S ), for example, is found chiefly in those regions of the tropical world where malaria is endemic. Hemoglobin S in its heterozygous form (inherited from one parent only) confers some immunity to those people who carry it, although it brings a deadly disease ( sickle cell anemia) in its homozygous form (inherited from both parents).

What are the physical variations of humans?

Contemporary scientists hold that human physical variations, especially in those traits that are normally used to classify people racially—skin colour, hair texture, facial features, and to some extent bodily structure— must be understood in terms of evolutionary processes and the long-range adaptation of human groups to differing environments.

What is the probability of rejecting a null hypothesis?

The experimenter can then review the probability of the treatment groups being the same and then decide whether to reject that they are or not. This decision point is referred to as rejecting the null hypothesis; the null hypothesis being that the variability of effects is due to normal biological variation, and hence groups are the same. By convention, we reject this hypothesis when the probability of making a false rejection is 5% or less. Hypothesis testing is discussed in more detail later.

What is normal biological variation?

The normal variability in the test species is called normal biological variation. The distribution of measurements typically follows a normal or Gaussian distribution. This distribution is described as a “bell-shaped” curve (as shown in Fig. 1 ), an essential underpinning of many statistical analyses. In essence, this is the background of “noise” against which backdrop observations are made. Mathematics can help clarify whether the results seen in an experiment are a result of biological “noise” or a treatment-related “signal.” Just as the experimenter cannot be sure that the treatment did have an effect, statistical analyses do not give a definite yes or no answer, rather a probability statement.

How does biological variation affect our lives?

Biological variation is central to all our lives. Diversity in our own species is recognized in a number of visible characteristics, such as height, and functional characteristics, such as biotransformation abilities. The latter source of variability has led to the developing field of pharmacogenomics. Unfortunately, biological diversity interferes with efforts to test treatment effects, even when the experiment is designed and controlled a priori. No matter how inbred study animals are, and consequently how alike their physiological responses are likely to be, there is always a range of response displayed in measurements made on these animals. This fact has been confirmed many times in monozygotic human twins, and more recently in cloned animals.

What is the goal set up of analytical variation?

The goal set-up is that variance due to analytical error should not exceed 20% of the variation ( Fraser, 1983 ). It can be shown that this is acceptable when CV analytical ≤1/2CV intra-individual or ≤1/2CV biological ( Fraser and Harris, 1989 ).

Why is diversity important in biology?

Within each species, diversity is essential for survival and finding a niche in which to develop. Without exploring the theory of evolution, diversity in our own species is recognized in a number of visible characteristics, such as height, and functional characteristics, such as biotransforming abilities. The latter source of variability has led to the developing field of pharmacogenomics. Unfortunately, biological diversity interferes with efforts to test treatment effects, even when the experiment is designed and controlled a priori. No matter how inbred study animals are, there is always a range of response displayed in measurements made on these animals.

What is radiotherapy schedule?

Radiotherapy schedules aim to maximize tumor cell kill while minimizing normal tissue damage, but they predominantly treat populations rather than individuals. Obviously there is some individualization of treatment based on clinical parameters such as stage, volume, and position of a tumor.

What happens when you measure health effects?

Whenever health effects are measured, biological variation and random errors in the measurement procedure will affect the results so that false-negative and false-positive results will occur. The ideal test of effects gives only true-positive and true-negative results, but such tests are difficult to find.

What is genomic testing?

Instead, genomic testing for variants that influence traits that are deeper than skin can be used to understand how their genomes might influence their health . Variations in Human Skin Color. Another area where our understanding of biology has greatly advanced is in the genomics of skin color.

What is NHGRI in health?

NHGRI - Method for Introducing a New Competency: Genom ics (MINC) - Integrating Genomics into Practice. If you'd like to know more about human genomic variation, you can participate in a number of research studies. The National Institutes of Health is leading the United States's All of Us Research Program.

How did the Human Genome Project change the world?

The Human Genome Project has also led to a change in our understanding of human traits and how we teach them - one example is eye color. For many years, students were taught that one dominant gene controlled brown or blue eyes and that blue-eyed parents could not have brown-eyed children. Scientists knew that the blue-eyes trait was actually more complicated despite what was taught in schools, but technology developed during and after the Human Genome Project helped pinpoint the actual combination of genomic variants that determine eye color. In fact, at least ten genes each of which comes in several "flavors," contribute to eye color. It is the combination of these gene variants in a person's genome that produces the wonderful range of human eye colors. Other traits are even more complicated; for example, around 80 percent of a person's height is controlled by more than 700 genomic variants, each one having a very small influence.

Why do people with AKT1 not look the same?

Each person with the syndrome does not look the same because they have different areas of skin overgrowth, and we now know this is because the genomic variant occurred in a different set of cells.

Why do scientists use one reference sequence?

When scientists agreed to use the one "reference" human genome sequence generated by the Human Genome Project [see DNA Sequencing ], it became easier to determine differences among people's genomes on a much larger scale.

What is the name of the disease that causes overgrowth of skin?

For example, Joseph Merrick, the subject of the book and movie "The Elephant Man," is thought to have had a disease called Proteus syndrome, which causes overgrowth of skin or other tissues.

What have we learned about genetic variation?

One of the most astonishing things that we have learned about human genomic variation is that we cannot always predict the effect of a given variant. Sometimes there are clear relationships, such as for red hair (the hair color of most redheads is due to one of three single-base changes in a particular gene). But a large study that started in 2012 has shown that each human is walking around with an average of 200 genes that are broken; for about 20 of those genes, both copies (one inherited from each parent) are not working, so there is a " loss-of-function ." Surprisingly, in some people, one of those 20 doubly broken genes was previously thought to be responsible for a genetic disease. We would think a person with such a mutation should be sick, but for some reason they are not! Are they "genetic superheroes?" Or are they just more resilient to these genomic variants for reasons that we don't yet understand?

What was the change in total cholesterol after Niaspan?

After addition of Niaspan, the patient came back in March and had a lipid profile. The actual changes of the analytes were -26.7% for total cholesterol, -29.8% for LDL cholesterol, 6.8% for HDL cholesterol, and -46.2% for triglycerides. Her total cholesterol change was more than the RCV of 95%, so the change of her total cholesterol was significant. So was LDL cholesterol: the actual change was 29.8%, and the RCV of 95% was 24.4%.

What is the RCV of significant change?

For total cholesterol, RCV of significant change is calculated to be 17.5%, using the analytical variation of 2.0% and within-subject variation of 6.0%. The within-subject variation of total cholesterol is taken from the book Biological Variation: From Principle to Practice by Callum G. Fraser. The actual change of total cholesterol was calculated to be 21.3%. The actual change was larger than the RCV of significant change, and therefore the change of total cholesterol level from 225 to 273 mg/dL was significant.

What is the RCV of a reference change?

Reference Change Value (RCV) will help us to understand whether the change of an individual’s serial result is statistically significant. RCV is determined by Z score, analytical variation (CV A), and within- subject variation (CVI), assuming that pre-analytical variation (CVP) is negligible. Z score is defined as a number of standard deviations that a result is from the mean. Z score of 1.96 indicates a probability of 95%, statistically significant. When Z score is 2.58, it indicates the change would have a probability of 99%, therefore statistically highly significant. Whether Z score of 1.96 or 2.58 should be used depends on the clinical contexts. In the rest of this lecture, Z score of 1.95 or RCV of 95% will be used.

What are the factors that affect the results of a test?

The test results of an individual person vary over time due to three factors: pre-analytical variation (CVP), analytical variation (CVA), within-subject biological variation (CVI). Pre-analytical variation is influenced by preparation of the individual for sample collection, sample collection itself, and conditions that the collected samples experience after collection prior to the samples being measured. Analytical variation is the imprecision of the measurement. Within-subject variation, as I explained earlier, is the random fluctuation around a homeostatic point.

What are the two types of biological variation?

There are two types of biological variations: within-subject and between-subject. Within-subject variation is the random fluctuation around a homeostatic point. In individuals, the homeostatic points usually vary. The variation between individuals is called between-subject biological variation.

What is the population based reference range?

Traditionally, population-based reference range is determined as 90% confidence intervals for the 95th percentile reference limits at the 2.5th and 97.5th percentiles. Population-based reference ranges are often used to interpret patients’ lab results.

How to determine biological variation?

Within-subject and between-subject biological variations are determined by conducting a biological variation study. The first step of the study is to recruit study subjects of interest. The study subjects can be healthy or patients with stable diseases depending on the contexts of the study. The second step is to take serial samples from study subjects at regular intervals that are consistent with the intended use of the tests. Next, the samples are analyzed in duplicates, and statistical techniques such as analysis of variance (ANOVA) are used to determine the analytical, within-subject, and between-subject biological components of variations.

What is the significance of biological variations?

To understand the significance of biological variations, it is essential to understand other key terms, such as health disparities, health care disparities, health inequities, and health inequalities . These terms have augmented significance when health care professionals attempt to render culturally competent care to diverse, multicultural groups of people.

Why is genetics important?

Population genetics is extremely important because human beings tend to marry or mate with people primarily like themselves—that is, the same racial, ethnic, and cultural groups.

How do African Americans compare to whites?

Weight differs in individuals both by race and by gender. African-Americans and Whites are less similar in weight than they are in height. This is believed to occur because African-Americans have heavier bone and muscle mass than Whites ( ; ). On the average, African-American men weigh less than their White counterparts (166.1 lb compared to 170.6 lb, respectively) ( ). In stark contrast, African-American women are consistently heavier at every age group than their White American counterparts (149.6 lb compared to 137.0 lb, respectively). In addition, African-American women average about 20 lb heavier than their White American counterparts from 35 to 65 years of age ( ). Similarly, Mexican American Whites, on the average, weigh more than non-Hispanic Whites as a result of truncal fat ( ). On average, obesity is more pronounced in the lower class, less pronounced in the middle class compared with their lower-class counterparts, and even less pronounced in the upper class compared with their middle-class counterparts ( ).

What are cultural differences?

Cultural differences are evident in communication, spatial relationships and needs, social organizations (family, kinships, and tribes), time orientation, and ability or desire to control the environment. Less recognized and understood are the biological differences among people in various racial groups.

Why are there differences in skin color?

When working with people from diverse cultural backgrounds, the nurse should understand how different races evolved in relation to the environment. Biological differences noted in skin color may be attributable to the biological adjustments a person’s ancestors made in the environment in which they lived. For example, it has been scientifically postulated that the original skin color of humans was black ( ; ) and that white skin was the result of mutation and environmental pressures exerted on persons living in cold, cloudy northern Europe. The mutation is believed to have occurred because light skin was better able to synthesize vitamin D, particularly on cloudy days. It is believed that black skin became a neutral trait in climates where protection from the sun and heat of the tropics was not a factor ( ; ).

How common are Tori?

Tori are fairly common, with palatine tori occurring in up to 25% of the population in most racial groups studied. Mandibular tori occur in 7% of Whites, 2% of African-Americans, and 40% of Asians ( ). Another variation in body size and structure is attributable to muscle size and mass.

What are behavioral objectives?

Behavioral Objectives. 1. Articulate biological differences among individuals in various racial groups. 2. Relate the importance of knowledge of biological differences that may exist among individuals in various racial groups to the provision of health care by the nurse. 3.

What is intrasubject BV?

Intrasubject BV in terms of CV (CV I )= (CVT TI2 −CV A2) 1/2 where CV TI is the total intrasubject CV, that is, CV calculated from assayed values, and CV A is the within-run analytical variability in terms of CV.

How to ensure reliability of BV estimates?

To assure the reliability of BV estimates, several preanalytical factors should be controlled. Subject s should maintain their normal lifestyle and protected, as much as possible, from emotional and environmental changes during the time of sample collections. If samples are collected over multiple days, collection times should be within a narrow time range of the day. Sample collection should be performed by the same phlebotomist with the same tourniquet application time. Subjects should be allowed to rest for few minutes, and samples should be collected while subjects are in the same posture, for example, sitting or lying down.

How many subjects are used in BV assay?

More samples and subjects, if feasible, can be better but 4 samples from 10 subjects were used and seemed enough [8]. Typically, BV studies are conducted on healthy individuals who are not suffering from any disease or trivial conditions, for example, allergy or flu. Some [26–28] reported intrasubject BV in diseased subjects but, in such cases, disease should not be expected to change over the sampling time window.

Why is random sampling called random?

It has been called “random” for the lack of reasoning to explain why repeated BM measurements made on multiple samples from an individual at the same time or within a narrow time window, even under standardized conditions, produce variable, sometime considerable, results. This type of BV represents the fluctuation of the concentration of a constituent (BM) around its homeostatic set point, and it is expressed in terms of intrasubject coefficient of variation (CV I) [8,24,25].

What is the difference between CV and CV A?

Intersubject or within-group BV in terms of CV (CV G )= (CVT TG2 −CV A2) 1/2 where CV TG is the total intersubject CV, that is , CV calculated from assayed values, and CV A is the within-run analytical variability in terms of CV (assuming that all samples will be analyzed on a single run).

What was the cause of the Japanese fishing village disaster?

A dramatic environmental tragedy resulted in crippling human nervous conditions and birth defects that affected an entire generation in a Japanese fishing village (Berlin, 1986; Harada, 1978). Abnormal behavior, resembling frenzied dancing, in local cats was the first sign of trouble, but despite early concerns by veterinarians, disaster was not averted. The “dancing cats” of Minimata were early warnings that fish from the bay had been contaminated with toxic levels of methyl mercury. Animal disease epidemics should not be dismissed out of hand because they could forecast environmental chemical contamination and increased human health hazards.

How can animals help the environment?

Animals could help monitor the environment, giving early warnings of environmental contamination. Information from pet-owning households can usefully be incorporated into research projects and even the census of the human population. Collecting information on the medical histories and behavior of pets does not require deliberate experimentation on animals. Scientists at the National Research Council (1991) recommended that government and other institutions develop pet animal population surveys and structure investigations of their diseases and exposure to toxins to monitor human and environmental health. Pet owners spend time observing their pets' behavior and health. This type of information gathering, different from formal investigations, is part of being a responsible pet owner. In addition, animal owners can become aware of the identity and toxic nature of the various pesticides applied in or around their homes. Based on such observations, owners may conclude that a pesticide has caused an adverse effect and that humans in the same environment are also likely to have been exposed and at risk.

How much genetic variation is there in a population?

In general, however, an average of 85% of genetic variation exists within local populations, ~7% is between local populations within the same continent, and ~8% of variation occurs between large groups living on different continents. The recent African origin theory for humans would predict that in Africa there exists a great deal more diversity than elsewhere and that diversity should decrease the further from Africa a population is sampled.

What is the average nucleotide diversity?

Nucleotide diversity is the average proportion of nucleotides that differ between two individuals. As of 2004, the human nucleotide diversity was estimated to be 0.1% to 0.4% of base pairs. In 2015, the 1000 Genomes Project, which sequenced one thousand individuals from 26 human populations, found that "a typical [individual] genome differs from the reference human genome at 4.1 million to 5.0 million sites … affecting 20 million bases of sequence"; the latter figure corresponds to 0.6% of total number of base pairs. Nearly all (>99.9%) of these sites are small differences, either single nucleotide polymorphisms or brief insertions or deletions ( indels) in the genetic sequence, but structural variations account for a greater number of base-pairs than the SNPs and indels.

Why are variants rare?

Because of the common ancestry of all humans, only a small number of variants have large differences in freque ncy between populations. However, some rare variants in the world's human population are much more frequent in at least one population (more than 5%).

How did the founder effect affect the distribution of genetic variation?

The rapid expansion of a previously small population has two important effects on the distribution of genetic variation. First, the so-called founder effect occurs when founder populations bring only a subset of the genetic variation from their ancestral population. Second, as founders become more geographically separated, the probability that two individuals from different founder populations will mate becomes smaller. The effect of this assortative mating is to reduce gene flow between geographical groups and to increase the genetic distance between groups.

What causes genetic variation?

The second main cause of genetic variation is due to the high degree of neutrality of most mutations. A small, but significant number of genes appear to have undergone recent natural selection, and these selective pressures are sometimes specific to one region.

Why are SNPs still useful?

Neutral, or synonymous SNPs are still useful as genetic markers in genome-wide association studies, because of their sheer number and the stable inheritance over generations. A coding SNP is one that occurs inside a gene. There are 105 Human Reference SNPs that result in premature stop codons in 103 genes.

How many chromosomes are there in a human birth?

Chromosome abnormalities are detected in 1 of 160 live human births. Apart from sex chromosome disorders, most cases of aneuploidy result in death of the developing fetus ( miscarriage ); the most common extra autosomal chromosomes among live births are 21, 18 and 13.

Race in The Twentieth Century

• In the early 1900s, head shape was considered an innate “racial” trait that was inherited, with little environmental influence at work. This concept changed with the pioneering studies of Franz Boas (1858–1942). Boas demonstrated that the cephalic index (the ratio of head width to head length…

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