Neuroscience and Human Development One of the most noticeable aspects of human beings involves the changes in shape, size, form, and function of the individual from a newly formed fetus to a fully grown adult. As the single most successful organism on Earth, human beings have developed, through millions of years of evolutionary adaptations, integrated yet malleable systems involving biological, physiological, emotional and intellectual components. This paper will review some of the most prominent theories of human development, discuss the nexus of human development and the neurological processes involved in the human body, and analyze the development and life progression processes human beings experience from birth through death.

Much of the success of human beings is attributable to the very design of the human body; including a large bi-pedal body, a brain that is disproportionately large relative to that of body size, as well as an extended period of childhood, during which significant formative transitions occur (Ulijaszek et al., 2000). With an unusually large brain than other organisms on Earth, humans have certain, distinct advantages in the struggle for survival and dominance over other animals. For example, our ability to reason, to analyze, and interpret information quickly has provided a tactile and strategic advantage over would be predators. Our innate abilities, limited as they may be at birth, are honed as we develop new skills sets during infancy, early childhood and adolescence. By adulthood, with some luck, humans have had time to develop behaviors through learning and activities that provide us an opportunity to be successful, social, problem-solving beings.

Human growth and development encompasses a wide spectrum of attributes for the human being; structural, behavioral, physiological, humanistic, psychological, and cognitive skills are but a few of the developments that humans undergo during the life span. While many life span and human development theories attempt to provide a descriptive analysis, a theoretical framework for understanding the myriad changes humans experience from fertilization to death, such theories do not seemingly account for the varieties of humans, the differences among each human being and the unique qualities that make each of us an individual. With that in mind, it is best to understand theories of human development as guidelines, as a foundation for better understanding humans in a general sense. However, this isn't to suggest that such theories are not beneficial or utilitarian. From a practical perspective, human development theories can provide people with an increased awareness of the self during the life span. With an increased awareness and a desire to reflect, knowledge and intellect provide the human being with, arguably, an important ability that further serves to separate us from other animals; our ability to think about our own thinking, to metacognate and contemplate the "meaning" of life. In turn, our ability to fully become sentient is realized. With an increased awareness and daily advances in technology, only now are we able to fully recognize and appreciate the intricacies of our own bodies, our own minds so that we can help those in need. For example, with current medical knowledge, we are able to mend the weak and provide for meaningful care for those who are nearing end of life. While human development theories and life span theories are as numbered as they are varied, several prominent theorists stand apart in our attempt to better understand the changes that occur during life.

In an effort to develop viable and reliable models of human development through the entire life course, some theorists have attempted to extend the range of human development theories, rather than simply focus on the formative stages of development that occur in early childhood. Kastenbaum (1993) observes that so called disengagement theory was the first substantive and innovative theory to consider the middle and later adult years; consequently, the term 'mid-life' crisis emerged as an influential alternative a few years later.

Life span theories and human development theoretical models form the foundation for understanding adult development as well as the aging process.

Sigelman and Rider (2006, pg. 2) define development as the entire set of "systematic changes and continuities" that occur in the individual from birth to death. These systematic changes and continuities occur in three broad domains: physical development, cognitive development and psychosocial development (Sigelman and Rider, 2006). Physical development, of course, includes normative physical attributes during the growth and decline of the human body, including the proper functioning of all combined physiological systems, physical manifestations of aging, sensory-motor responses, as well as the collective physical accommodations that humans develop as a result of the aging process (Sigelman and Rider, 2006). Cognitive development includes the set of changes and adaptations...

Psychosocial development, Sigelman and Rider (2006, pg. 3) note, include "interpersonal aspects of development, such as motives, emotions, personality traits, interpersonal skills and relationships, and roles played in the family and in the larger society." With this working definition of human development, it is important to note that life span theorists do not all agree on either the ways in which people grow and develop, or exactly why people develop they way that they do.
All developmental theories involve some element of progression from one stage to another. This progression, however, does not necessarily mean "change." Life stage development theorists differ on the nuisances of each life stage, but seem to agree that incremental progressions throughout the lifespan provide for unique and identifiable segments in human development. Again, this is not to suggest that "progression" imparts a sense of "better" or "improved."

Life span perspectives suggest that an individual's adult experiences should be contextualized; that childhood and adolescence are integral components, involving a myriad of experiences, thoughts, and feelings that must be considered to understand the adult. Dividing human development into two distinctly separate phases, the life-span perspective involves both an early phase (childhood and adolescence) and a later phase (young adulthood, middle age, and old age). "The early phase is characterized by rapid age-related increases in people's size and abilities. The later phase is defined by slow changes in size while abilities continue to develop in response to the environment adaptation" (Cavanaugh, 2005, pg. 3).

Adult development is a complex, multi-faceted phenomenon; understanding how an adult develops requires a variety of perspectives. Such perspectives may include behavioral, physiological, and cognitive approaches (Cavanaugh & Fields, 2006). Within the gambit of intellectual functioning, cognition refers to the processes through which knowledge is acquired and problems are solved. Cognitive development refers not just to the structural development of the brain but also to the development of one's knowledge as well. Piaget indicated that the highest cognitive stage of development for adult people is formal operations, suggesting that some adults progress beyond formal operations to more advanced forms of thought (Sigelman & Rider, 2009). With this in mind, this study focuses on the cognitive aspect of growth and development of the adult. Specifically, this research aims to provide an in-depth discussion about the brain and neuroscience and its relation to adult development and learning.

The Human Brain and Neuroscience

All organisms receive information in the form of some external stimuli; to process information received, and to produce appropriate responses. While this process may take only a fraction of a second, it is interesting to note that, for most living organisms, these functions are performed by two interconnected systems working in tandem to provide the human with a viable set of reactionary responses; the nervous system and the endocrine system.

The Nervous System

The nervous system is composed of large networks of nerve cells that perform three interconnecting functions. First, the nervous system allows organisms to receive information from a variety of sensory modalities in the well-functioning human being; sight, smell, touch, taste and sound all provide people with a range of stimuli every day. How the human brain processes such information, as well as how the nervous system responds to brain signals, dictates how people react and feel in a given situation. Harris (2010) notes that the nervous system provides responses to stimuli quickly given that the speed of the information transmission is achieved by electrical and chemical impulses within and between nerve cells. The nervous system allows an individual to respond, act appropriately in response to the perceived stimuli primarily by controlling muscles and glands. The three functions can be accomplished within a few milliseconds (Harris, 2010).

The nervous system is bifurcated into two separate systems: the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and the spinal cord while the peripheral nervous system subsists outside the central nervous system comprised of nerves and ganglia.

The peripheral nervous system consists of two separately functioning components: the sensory division and the motor division. The sensory division provides appropriate responses from sensory receptors to the central nervous system. Sensory neurons transmit reactive responses from the periphery to the central nervous system while the motor division conducts action potentials from effector organs such as muscles and glands. In contrast, motor neurons transmit action potentials from…