Key Biological Changes During Adulthood Explained
Adulthood can be described as the period in every human life in which they are under complete maturity of physical and intellectual well-being. The adult stage is the period of every human being when parental control is lost and everyone is assigned their responsibilities. In legal terms, the adulthood stage is the time in human life when they reach the major age which means they become self-reliant and decisive. Mature adulthood also indicates the development of psychological and sexual maturity. Several different events take place during the transition period of a human being from childhood period to adulthood period.
What is Adulthood?
To define adulthood biologically, it is usually determined by the onset of secondary sex characteristics in both male and females. In males the secondary sex characteristics include behaviour like ejaculation, features like facial hairs, deepening of voice and growth of pubic hairs are seen. In females, the secondary characteristics of adulthood include features like the development of breasts, starting of menstruation. During earlier days, the adult stage marked the onset of time for individuals to go out and work and support their families. Since in the olden times' education or school was not given much importance, children soon after reaching the adulthood stage could work independently without any prior experience.
To describe what is adulthood legally, the adult stage can be defined as the major age of self-reliance and responsibilities.
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Adulthood Age Range
The adulthood age range is commonly considered to begin at the age of 20 or 21 years. Our middle age starts at the age of 40 which is then followed by our old age which commences at the age of 60. The age for the commencement of legal adulthood might vary from one country to another. Usually, the legal adult stage starts at the age of 18.
Adulthood can also be further classified as:
The Early Adulthood Stage: This adulthood stage lies in the adulthood age range of 22-34.
The Early Middle Age: This adulthood stage lies in the adulthood age range of 35-44.
The Late Middle Age: This adulthood stage lies in the adulthood age range of 45-64.
Late Adulthood: This adulthood stage lies in the adulthood age range of 65 and above.
Adulthood and Related Changes in the Body
The adult stage is marked by the slow decline of body functions in the later period. Although we find that the muscles increase till the middle of 20s and the mass of the skeleton increases till the age of 30s, soon there is a decrease in growth and cellular and nervous activity. Sexual activity might also be hampered in both males and females. A decline in the nervous activity of older adults is marked by changes in the electrical activity of the brain. Older adults might face changes in their learning ability, their movement and also can face impaired visual sensation and other physical problems. The older part of mature adulthood slowly leads an individual to age.
Did You Know?
Although the learning capacity of young adults, that is their trait to organize newly gained information, is much faster than the old adults, the capacity of retention of information in general that is to accumulate knowledge is much more in old adults.
Typically the age for attaining adulthood is 18. However, adulthood also depends on the psychological behaviour of an individual. A person even after attaining biological maturity can behave like a child. Again a child with no biological maturity can behave like an adult.
Conclusion
Adulthood is thus marked by several physiological and psychological changes in the human body. It is the phase when an individual learns to make decisions and live an independent life. Most of the individuals start families of their own during this time. This is the time in the life of every individual when a single action or decision can have a huge impact on his/her life and society at large.
FAQs on Adulthood in Biology: Definition, Stages & Role
1. What is adulthood from a biological perspective?
From a biological perspective, adulthood is the stage in an organism's life cycle that follows adolescence and is primarily defined by the attainment of sexual maturity and the capability to reproduce. It also signifies the completion of major physical growth, where an individual reaches their full height and skeletal development. This stage is characterised by relative stability in physiological functions before the onset of senescence or aging.
2. What are the three main stages of adulthood, and what are their typical age ranges?
Adulthood in humans is generally divided into three main stages, each with distinct biological and psychological characteristics. The age ranges are approximate and can vary based on individual and environmental factors. The stages are:
- Early Adulthood: Typically spans from the late teens or early twenties to around age 40. This stage is marked by peak physical health, strength, and reproductive capacity.
- Middle Adulthood: Generally considered to be from age 40 to about 65. During this period, the first signs of aging, such as a decline in sensory acuity and changes in metabolism, begin to appear.
- Late Adulthood: Begins around age 65 and continues until the end of life. This stage is characterised by a more pronounced decline in physical abilities and an increased susceptibility to age-related health issues.
3. What key physical and hormonal changes mark the transition into early adulthood?
The transition into early adulthood is marked by the completion of puberty and the stabilisation of the body's systems. Key changes include the achievement of peak bone density and muscle mass. Hormonally, levels of sex hormones like testosterone in males and estrogen in females stabilise, regulating mature reproductive functions, such as the menstrual cycle in females and spermatogenesis in males. The sensory organs, including vision and hearing, are at their sharpest, and the cardiovascular system operates at maximum efficiency.
4. How do cognitive and psychological abilities develop during early and middle adulthood?
During early adulthood, cognitive development often moves beyond formal logic to what is known as postformal thought. This involves integrating logic with practical experience and emotion, leading to more flexible and adaptive problem-solving. Psychologically, this is a crucial period for forming intimate relationships and establishing a career and personal identity. In middle adulthood, cognitive abilities like vocabulary and verbal memory can remain strong or even improve, while psychological focus often shifts towards mentorship, contributing to the next generation (generativity), and re-evaluating life's achievements.
5. Why is early adulthood often described as the peak of human physical performance?
Early adulthood is considered the peak of physical performance because multiple biological systems are functioning at their optimal level simultaneously. The musculoskeletal system has reached maximum strength and bone density, the cardiovascular system provides efficient oxygen transport, and the nervous system ensures the fastest reaction times and sharpest senses. Furthermore, the body's cellular repair mechanisms and metabolic rate are highly efficient, allowing for quick recovery from physical exertion and injury, a combination of factors that is unique to this life stage.
6. How does the biological definition of adulthood contrast with its legal and social definitions?
The definitions of adulthood contrast significantly across different domains:
- Biological Definition: Focused entirely on physiological markers, primarily the ability to reproduce and the completion of physical growth. It is a gradual process, not a single event.
- Legal Definition: A sharp, specific age defined by law (e.g., 18 years in India) that grants certain rights and responsibilities, such as voting, signing contracts, and being tried as an adult. It is an abrupt, socially constructed threshold.
- Social Definition: Based on achieving certain cultural milestones, such as completing education, gaining financial independence, marrying, or starting a family. This is the most variable definition, as these milestones differ across cultures and historical periods.
7. What is the biological significance of the aging process that begins in middle and progresses into late adulthood?
The biological significance of aging, or senescence, is a complex topic with several theories. From a physiological standpoint, it represents a gradual decline in the body's ability to maintain homeostasis and respond to stress, leading to decreased function and increased vulnerability to disease. Evolutionarily, one theory suggests aging is a trade-off where genes that are beneficial for reproduction in early life may have detrimental effects later on (antagonistic pleiotropy). Another perspective is that after the reproductive phase, there is less selective pressure to maintain the body's integrity. Socially and evolutionarily, the post-reproductive stage can be significant for kin selection, where older individuals contribute to the survival of their offspring and relatives (the 'grandmother hypothesis').
