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Grandmother Hypothesis
The grandmother hypothesis is a hypothesis to explain the existence of menopause in human life history by identifying the adaptive value of extended kin networking. It builds on the previously postulated "mother hypothesis" which states that as mothers age, the costs of reproducing become greater, and energy devoted to those activities would be better spent helping her offspring in their reproductive efforts. It suggests that by redirecting their energy onto those of their offspring, grandmothers can better ensure the survival of their genes through younger generations. By providing sustenance and support to their kin, grandmothers not only ensure that their genetic interests are met, but they also enhance their social networks which could translate into better immediate resource acquisition. This effect could extend past kin into larger community networks and benefit wider Inclusive fitness, group fitness. Background One explanation to this was presented by George C. Williams ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundary, maritime boundaries with the Pacific Ocean to the west, the Caribbean Sea to the southeast, and the Gulf of Mexico to the east. Mexico covers 1,972,550 km2 (761,610 sq mi), and is the List of countries by area, thirteenth-largest country in the world by land area. With a population exceeding 130 million, Mexico is the List of countries by population, tenth-most populous country in the world and is home to the Hispanophone#Countries, largest number of native Spanish speakers. Mexico City is the capital and List of cities in Mexico, largest city, which ranks among the List of cities by population, most populous metropolitan areas in the world. Human presence in Mexico dates back to at least 8,000 BC. Mesoamerica, considered a cradle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutations
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronary Artery Disease
Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of cardiovascular disease, heart disease involving Ischemia, the reduction of blood flow to the cardiac muscle due to a build-up of atheromatous plaque in the Coronary arteries, arteries of the heart. It is the most common of the cardiovascular diseases. CAD can cause stable angina, unstable angina, myocardial ischemia, and myocardial infarction. A common symptom is angina, which is chest pain or discomfort that may travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn. In stable angina, symptoms occur with exercise or emotional Psychological stress, stress, last less than a few minutes, and improve with rest. Shortness of breath may also occur and sometimes no symptoms are present. In many cases, the first sign is a Myocardial infarction, heart attack. Other complications include heart failure or an Heart arrhythmia, abnormal h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alzheimer's Disease
Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, self-neglect, and behavioral issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to twelve years. The causes of Alzheimer's disease remain poorly understood. There are many environmental and genetic risk factors associated with its development. The strongest genetic risk factor is from an allele of apolipoprotein E. Other risk factors include a history of head injury, clinical depression, and high blood pressure. The progression of the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteoarthritis
Osteoarthritis is a type of degenerative joint disease that results from breakdown of articular cartilage, joint cartilage and underlying bone. A form of arthritis, it is believed to be the fourth leading cause of disability in the world, affecting 1 in 7 adults in the United States alone. The most common symptoms are joint pain and Joint stiffness, stiffness. Usually the symptoms progress slowly over years. Other symptoms may include joint effusion, joint swelling, decreased range of motion, and, when the back is affected, weakness or numbness of the arms and legs. The most commonly involved joints are the two near the ends of the fingers and the joint at the base of the thumbs, the knee and hip joints, and the joints of the neck and lower back. The symptoms can interfere with work and normal daily activities. Unlike some other types of arthritis, only the joints, not internal organs, are affected. Possible causes include previous joint injury, abnormal joint or limb development ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteoporosis
Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in Bone fracture, fracture risk. It is the most common reason for a broken bone among the Old age, elderly. Bones that commonly break include the vertebrae in the Vertebral column, spine, the bones of the forearm, the wrist, and the hip. Until a broken bone occurs there are typically no symptoms. Bones may weaken to such a degree that a break may occur with minor stress or spontaneously. After the broken bone heals, some people may have chronic pain and a decreased ability to carry out normal activities. Osteoporosis may be due to lower-than-normal peak bone mass, maximum bone mass and greater-than-normal bone loss. Bone loss increases after menopause in women due to lower levels of estrogen, and after andropause in older men due to lower levels of testosterone. Osteoporosis may also occur due to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reproductive Success
Reproductive success is an individual's production of offspring per breeding event or lifetime. This is not limited by the number of offspring produced by one individual, but also the reproductive success of these offspring themselves. Reproductive success is different from fitness in that individual success is not necessarily a determinant for adaptive strength of a genotype since the effects of chance and the environment have no influence on those specific genes. Reproductive success turns into a part of fitness when the offspring are actually recruited into the breeding population. If offspring quantity is not correlated with quality this holds up, but if not then reproductive success must be adjusted by traits that predict juvenile survival in order to be measured effectively. Quality and quantity is about finding the right balance between reproduction and maintenance. The disposable soma theory of aging tells us that a longer lifespan will come at the cost of reproduction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patriarchal
Patriarchy is a social system in which positions of authority are primarily held by men. The term ''patriarchy'' is used both in anthropology to describe a family or clan controlled by the father or eldest male or group of males, and in feminist theory to describe a broader social structure in which men as a group dominate society. Sociobiologists compare human gender roles to sexed behavior in other primates and argue that gender inequality originates from genetic and reproductive differences between men and women. Patriarchal ideology explains and rationalizes patriarchy by attributing gender inequality to inherent natural differences between men and women, divine commandment, or other fixed structures. Social constructionists sociologists tend to disagree with biological explanations of patriarchy and contend that socialization processes are primarily responsible for establishing gender roles, they further argue that gender roles and gender inequity are instruments of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philopatry
Philopatry is the tendency of an organism to stay in or habitually return to a particular area. The causes of philopatry are numerous, but natal philopatry, where animals return to their birthplace to breed, may be the most common. The term derives from the Greek roots ''philo'', "liking, loving" and ''patra'', "fatherland", although in recent years the term has been applied to more than just the animal's birthplace. Recent usage refers to animals returning to the same area to breed despite not being born there, and Animal migration, migratory species that demonstrate site fidelity: reusing stopovers, staging points, and wintering grounds. Some of the known reasons for organisms to be philopatric would be for mating (reproduction), survival, migration, parental care, resources, etc.. In most species of animals, individuals will benefit from living in groups, because depending on the species, individuals are more vulnerable to predation and more likely to have difficulty finding res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatogenesis
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the Mitosis, mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called Spermatogonial Stem Cells, spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. The primary spermatocyte divides meiotically (Meiosis I) into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. These develop into mature spermatozoa, also known as sperm, sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatoz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Senescence
Senescence () or biological aging is the gradual deterioration of Function (biology), functional characteristics in living organisms. Whole organism senescence involves an increase in mortality rate, death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's biological life cycle, life cycle. However, the resulting effects of senescence can be delayed. The 1934 discovery that calorie restriction can Life extension, extend lifespans by 50% in rats, the existence of species having negligible senescence, and the existence of potentially immortal organisms such as members of the genus ''Hydra (genus), Hydra'' have motivated research into Life extension, delaying senescence and thus age-related diseases. Rare human mutations can cause accelerated aging diseases. Environmental Gerontogens, factors may affect aging – for example, overexposure to ultraviolet radiation accelerates skin aging. Different parts of the body may age at different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hadza People
The Hadza, or Hadzabe (''Wahadzabe'', in Swahili), are a protected hunter-gatherer Tanzanian indigenous ethnic group, primarily based in Baray, an administrative ward within Karatu District in southwest Arusha Region. They live around the Lake Eyasi basin in the central Rift Valley and in the neighboring Serengeti Plateau. As descendants of Tanzania's aboriginal, pre- Bantu expansion hunter-gatherer population, they have probably occupied their current territory for thousands of years with relatively little modification to their basic way of life until the last century. They have no known close genetic relatives and their language is considered an isolate. Since the first European contact in the late 19th century, governments and missionaries have made many attempts to settle the Hadza by introducing farming and Christianity. These efforts have largely failed, and many Hadza still pursue a life similar to their ancestors. Since the 18th century, the Hadza have come into in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
