Some have argued that mammalian brain development is constrained by a variety of factors, including a physiological necessity to develop in an overall isometric pattern. However, Hager, Lu, Rosen, and Williams (2012) argued against that position. Based on observations, they recognized that mammals of the same species with brains that were matched according to weight, frequently exhibited significantly different sizes in Cross subject comparisons of the same brain region. To further evaluate this, they analyzed over 10,000 mice noting several different regions of the brain and made comparisons. They did not find any significant phenotype correlation, thus supporting what is referred to as the Mosaic model of brain evolution. Furthermore, they …show more content…
were able to show that brain size is governed by a different mechanism is body size. This academic disagreement serves as an illustration of just how much disagreement there is in the field regarding the evolution of the brain. A wide variety of hypotheses have been put forth that provide clues as to some of the factors that are related or that cooccur with the evolutionary morphology of the brain, however conclusive models are still lacking. This paper will review a variety of these factors in an effort to understand some of the biochemical factors that needed to be available before a brain as large as that of Homo sapiens was able to develop. History and Development of the Brain The brain is an electrochemical organ that governs nearly every aspect of the internal and external behaviors of those organisms fortunate enough to possess one.
Clearly not all organisms possess a brain, and there is a vast range of brains in terms of size, composition, structure, degree of sophistication, and functional areas of specialization. However, not all organisms are in need of a brain. Historically, a great deal of research regarding sensitization and learning has been conducted using a marine invertebrate, the Aplysia. Specifically, the sensitization studies that have been performed on tens of thousands of these mollusks have revealed a great deal of information on the neurophysiological and neurochemical adaptations that occur during the development of sensitization and habituation (Cooper, Bloom, & Roth, 1996). In considering this, one must understand that the effect of the sensitization can last over an extended period of time before finally returning to baseline levels. What is this, if not memory? How is it possible for an invertebrate mollusk to retain information and behave in a manner that requires the acknowledgment of some type of memory? The answer is very simple. Apex animals such as humans remember things in the same way: we undergo a series of neurochemical and morphological changes that actually modify the structure of our brains, at least at the level of the neuron. If these changes are reinforced by repeated excitation of the specific neural pathways involved in storage or retrieval of the memory, or in the afferent to efferent pathways in the case of behavioral matters, the changes become long-lasting, or even permanent. Conceptually, the memory process of Homo Sapiens with our elaborate and elegant brains, and the Aplysia, with its simple, non-centralized nervous system, is the
same. What Is a Brain Despite the adaptive similarities in the respective nervous systems, the nervous system of Aplysia does not qualify as a brain. The responsiveness and adaptation of the Aplysia are based upon feedback mechanism. The behavior is, essentially, a reflex, similar to the feedback in humans when significant damage is being done to a body part. For example, when a person touches a hot stove the afferent signals reach the spinal cord and activate a feedback mechanism that sends an efferent signal to immediately pull the hand away from the stove. It is a reflexive act that does not require higher processing. This is the same system at work in the Aplysia when it is touched and withdraws its mantle. A brain, however, is a cohesive organ unto itself that functions on a much grander scale. The difference is significant. While from a biobehavioral perspective or from a strictly behaviorist perspective as it would be referred to in the behavioral sciences, when attempting to understand the mechanism behind any given behavior, the only variable of interest is the observable behavior itself. This has led to a history of brain and neuroscience research based upon a stimulus-response model that seems to forget the more elaborate functioning of the brain. Raichle (2010) makes the point that such a paradigm creates or at least reinforces what he refers to as a reflexive view of brain function which, he elegantly argues, ignores significant evidence pointing to other functions of the brain that are not directly observable. Much of his argument is based upon observation of brain metabolism, specifically, glucose utilization. The brain uses a disproportionate amount of energy relative to other tissues. This has been referred to as the expensive tissue hypothesis (Aiello & Wheeler, 1995), which has found empirical support in a number of domains (Bordes, Mornad, & Krasnov, 2011; Kaufman, 2003; Pitnick, Jones, & Wilkinson, 2006). At its core, the expensive tissue hypothesis posits that as the brain uses approximately ten times the amount of energy predicted by its relative mass in the body, other tissues must function on a relatively reduced amount of energy; other organs or tissues must be reduced in size; or other activities that use a significant amount of energy must be eliminated or dramatically reduced. By extension, these conditions required physical, developmental, and social evolutionary changes to support the development and maintenance of such a large, disproportionately high energy organ. Brain Evolution The human brain is the result of millions of years of evolutionary change. The major developments in the evolution of the brain have traditionally been divided into three epochs as illustrated in Figure 1. The reptilian brain, the oldest evolutionary part of our current brain, centralized a great many functions and provided the ability to engage in a wide range of behaviors that previously were not possible. This early control center included components that governed breathing, alertness, and a variety of other non-reflexive behaviors. However, there is no indication that it provided for any cognition, emotional experience, or self-awareness (Eccles, 1992). These began to arise to some extent with the development of the paleomammalian brain. The question of how this development occurred is still an issue of debate. Significant advances in genetics have helped provide some clues, however, a wide variety of theories are still debated with no definitive answer. What is known is that the reptilian brain underwent a series of morphological changes that included significant migration of neurons in the development of a new type of architecture as the cerebrum evolved. For these migrations to have resulted in a value added arrangement, as opposed to changes that destroyed some functioning while creating other abilities, neural connections needed to adapt and retain connections to the nuclei, or the homologues thereof, with which they had been previously associated (Eccles, 1992; Puelles, 2001). The development of the paleomammalian brain, also known essentially as the limbic system, brought with it a wide range of changes. One of the most significant was the development of extensive and complex systems of emotion. Emotion can be a powerfully motivating force and therefore as the shift from reptile to mammal occurred, a wide range of behavioral changes were manifest as well. One of the significant developments that occurred was a dramatic shift in sociability. With these new emotions came increased variation in social needs and social responsiveness, which as we shall see, may have actually been necessary for the brain to evolve any further. Conservation of Energy As mentioned previously, the brain is a disproportionately high energy consumption organ. The expensive tissue hypothesis suggests that either the elimination or reduction of other high energy organs is required, and/or the ability of other tissues to survive on relatively less energy is required, and/or a reduction in other high energy activities is required. Empirically evaluating the potential requirement for the elimination or reduction of other high energy organs has been challenging as it has been difficult to find other organisms with a brain to body ratio approximating that of humans. However, Kaufman (2003) evaluated in this aspect of the hypothesis with the Gnathonemus petersii, a freshwater African fish, the brain of which accounts for 60% of the entire oxygen use of the fish. To evaluate this aspect of the hypothesis, Kaufman dissected five of the fish and evaluating their intestines relative to the intestines of two other species of fish used as matching sample controls, and 58 other types of fish through a meta-analysis published literature. Kaufman found that indeed there was a significantly reduced intestines system in the larger brained Gnathonemus petersii. Despite this, Navarrete, van Schaik, and Isler (2011) found no support for this position in humans when compared to 100 different species of mammals which included 23 Primates. Their position is that the evolution of the human brain was only possible due to a consistent, high quality diet, and a modification of behaviors requiring high energy consumption. Pontzer (2012) supports these suggestions and adds that a significant change in locomotion allowed for additional energy the diversion of energy from locomotion to cerebral development without a significant compromise and other high-energy behaviors such as reproduction. It is well documented that the energy cost of locomotion varies along species based on the type of locomotion used. Relative to buy patents, quadrupeds have a significantly higher energy cost, but only at walking speed. Running speed, bipeds use significantly more energy, which would by extension resulting in reduced energy available for the brain. It has also been shown that apes and chimpanzees expend a him him him great deal more energy in locomotion than do humans. It has been suggested that this supports another aspect of the expensive tissue hypothesis (see Leonard, Robertson, & Snodgrass, 2007, for in-depth review). Reproduction is clearly a high energy endeavor. Caring for the young is also a high energy endeavor. Additionally, human children are born with a significantly underdeveloped brain that does not reach maturity until roughly puberty. This extended period of development requires a great deal of maternal care which in most species would compromise reproduction. Allomaternal care has been suggested as a social adaptation that provides for energy conservation in the development and maintenance of a larger brain without the expense of reduced fertility or breeding (Isler & van Schaik, 2012). Conclusion The evolution of the brain from an array of neurons in a primitive nervous system that operates on feedback loops, to the advanced brain of Homo Sapiens is not yet entirely understood. Despite that, a great deal of physical, social, and behavioral changes have been identified that were prerequisites to the development and continued evolution of the brain.
Cephalopods are known to be exceptionally intelligent by invertebrate standards and in some respects even rival “higher” vertebrates. These animals have many highly evolved sensory and processing organs that allow them to gain a greater understanding of their environment and their place within it. Due to their advanced structures, many of which are analogous to vertebrate structures, and abilities they have been widely studied. Their methods of learning have been of prime interest and many experiments have been conducted to determine the different ways in which octopuses can learn. From these experiments four main kinds of learning have been identified in octopuses: associative learning, special learning,
Every parent desires to have a child who will be successful in life. In “Brainology” author, Carol Dweck explains that there are consequences for praising children for their work. Dweck also explains that there are different types of mindsets that enable an individual’s development. She claims that there are two types of mindsets that people have. In a growth mindset, people believe that their most basic abilities can be developed through dedication and hard work ( Dweck 1). Furthermore growth mindset individuals love learning and are resilience that is essential for great accomplishment. (Dweck 1). One more theory, Dweck mentioned was fixed mindset. The author states “In a fixed mindset, people believe their basic qualities, like their intelligence
Throughout and for many years there has been a lot of controversy on how to trial someone who has committed a crime under the age of 18. A lie will be a lie even if it 's serious or innocent and that 's why just like a crime will always be a crime, no matter what the situation is. The age of a person who has committed murder shouldn 't be an issue or a complication. Many advocate that the juvenile is just a child, but despised that I believe that is no justification or defense for anyone who does a crime. America and the nation need to apprehend that juveniles that are being conducted to life in prison is not just for one small incident or crime, but for several severe crimes according to Jennifer Jenkins, Juvenile Justice Information
...f we are to know anything about our own evolutionary history, we must begin by looking where it counts. If we discover that the methods we are using and the things we are looking at do not tell us what we want to know then we must reassess those methods and attempt to find ones that do tell us what we want to know. From looking at bone growth and development we have learned that the features we observe do not tell us what we thought they did. We must find a different way to study the traits that have bearing on the course of adaptive trends. By studying brain growth and organization we have a new place to look. Positional analysis provides a way for us to actually sort out the traits that are applicable and meaningful, such as how the processes of bone growth reflect brain growth. This allows us to continually check ourselves and keep from making the same mistakes.
These scientists reviewed the natural space-use patterns and hippocampal size in kangaroo rats after undergoing evolution by natural selection. The size of the hippocampus, a forebrain structure that processes spatial information, correlates with the need to relocate food caches by passerine birds and with sex-specific patterns of space use in microtine rodents. The influences on hippocampal anatomy of sexual selection within species, and natural selection between species, have not yet been studied in concert, however. Here we report that natural space-use patterns predict hippocampal size within and between two species of kangaroo rats (Dipodomys). Differences in foraging behavior suggest that Merriam''s kangaroo rats (D. merriami) require better spatial abilities than bannertail kangaroo rats (D. spectabilis). Sex-specific differences in mating strategy suggest that males of both species require more spatial ability than females. As predicted, hippocampal size (relative to brain size) is larger in Merriam''s than in bannertail kangaroo rats, and males have larger hippocampi than females in both species. Males of a third species (D. ordii) also have smaller hippocampi than Merriam’s kangaroo rat males, despite being similar to Merriam''s in brain and body size. These results suggest that both natural and sexual selection affect the relative size and perhaps function of mammalian hippocampus. They also reassert that measures of functional subunits of the brain reveal more about brain evolution than measures of total brain
An adult person who is illiterate and tries to read shows profound changes in deep brain. It came from a study where researchers helped illiterate woman from North India to read. In addition, the illiterate woman had scanned their brain before and after learning to read. The researchers found a big change in the brain after the women learned to read. They conclude that the brain of an adult is not flexible. The plasticity still actives in adult age.
Another major difference between primate and cetacean brains is that the primate brain favors the motor cortex, while "the cetaceans greatly favor the sensory region (and are not very balanced at all between the two)" (1). In the final measure of brain complexity, neural density ...
It has been proven that a child’s early years are the peak at which the mind can bend and shape, creating the foundation for a life. We know now that even before birth, the mind is a delicate matter that if improperly taken care of could alter a person’s entire life. Nourishment and stimulation before and after the birth of a child mold’s the brain in its most malleable state. Medical and scientific institutes paired with parenting information organizations have made information readily available for parents, childcare providers, and students to advise them of the importance of childhood brain development. This information is not only critical for the child, but for the person they will become in the future.
The mammalian brain contains several different memory systems, which can be divided into declarative and non-declarative memory systems. Declarative memory can be further divided into episodic and semantic memory, and non-declarative memory can be divided into priming, associative learning, and procedural memory.
The members of the Homo genus possess a combination of unique features that distinguish them from other related species. At the time that each respective species was alive, they were able to walk upright on two legs, use their large brains for the benefit of their species, and could thrive in many geographically and climatically diverse areas of the world. One of the most mysterious quandaries in science is how the lineage of the Homo genus became so different from their primate relatives. Bipedalism, brain size, and location diversity all have a common link that may explain this difference – dietary evolution allowed humans to adapt to their surroundings, and in turn, become a more advanced species. The Homo diet evolved in relation to food availability and nutritional necessity. With the ability to maintain a proper diet, the species of the Homo genus were able to flourish and advance toward the development of modern Homo sapiens.
The purpose of this paper to examine the evolution of the human brain that distinguishes them from other species based on the traits that humans possess: such as language, emotional complexity and consciousness. The significance of traits are due to adaptations in humans to promote the survival of our ancestors. Professor Hamilton (2012) discusses that the evolution of the human brain starts with the idea of the Triune brain, proposed by MacLean, whereby the human brain is made up of three parts: Reptilian, Paleo-mammalian, and Neo-mammalian. Animals with the neo-mammalian brain have a more complex brain compared to the other parts, since this is where the neocortex evolved. Humans essentially have this higher brain function which is responsible for our ability to think, make decisions, promote agency, and the ability to relate with each other. This concept fits into the evolutionary process since it shows how the complex the brain has become through evolutionary processes. In essence, as humans, we “have a rich, evidence-based understanding of our behavior that can lead us to plan to be ‘better’ or ‘more successful’ people” according to Professor Hamilton (2012). Thus, shows how evolution plays a significance in understanding human behavior and comparing humans with other species.
In order to understand the functional relationship between learning and memory we have to first define what both learning and memory are. Learning can be described as “the acquisition of knowledge or skills through experience, practice, or study, or by being taught” (Merriam-Webster, 2014). “Memory is the means by which we draw on our past experiences in order to use this information in the present” (Sternberg, 1999). Base on this definitions one can conclude memory is essential part of our lives. Without any memory of the past, we would not be able to operate in the present or reminisce about the future. We would not be able to remember what we did a few days ago, what we have accomplished today, or what we intend to do tomorrow. Without memory our ability to learn would not exist. Learning and Memory are linked to our cognitive abilities as well as that of animals. An example that can be used to show the relationship between learning and memory is the study of how a rat behaves in a maze. As we all know rats have been used in experimental mazes since at least the early 20th century. Hundreds if not thousands of studies have looked at how rats run different types of mazes, from T-maze, to radial arm mazes, and to water mazes. These maze studies help scientist study spatial learning and memory in rats. Maze studies helped us uncover general principles about learning that can be applied to several species, including mankind. In today’s modern societies, mazes tend to be used to determine whether different treatments affect learning and memory in rats. According to Kolata al, 2005 case study the tasks that comprise the learning battery were specifically chosen so that each one placed specific sensory, motor, motivational, and info...
"Patterns of activity in small, more primitive areas of the brain are recapitulated in larger, more advanced parts," Sutton says. "This means that nature did not have to develop new rules of operation for different levels of the brain from small clusters of cells to large systems."
Brain Development is a nonstop development, we never stop learning so our brain isn’t going to just stop I mean well when it’s our time, but it won’t as long as you continue to learn and grow. The human brain begins to develop as early as three weeks after conception. But our brain development is a lifetime process. It doesn’t just stop developing at a certain age. There is a difference in brain development in children and adults the early life is impressionable then in the maturity aspect of life. This is a positive thing because as children they learn new thing they’re open to new and exciting things but then again it can be negative because children tend to be vulnerable to development problems. Our brain develops not only from nurture
Over 40 years ago, Henry Jerison identified a key difference between primates and all other vertebrates: primates have unusually large brains for their body size (Dunbar 2009). Initially, it was assumed that the evolution of large brains in primates was guided by ecological problems, such as foraging and other acts of survival. Today, the widely accepted theory is that there is a link between social complexity and brain expansion, and large brains in primates evolved as a means to manage their complex social lives - this explanation is known as the “social brain hypothesis.” The purpose of this paper is to not only examine the mechanisms underlying the social brain, but to also explore how it relates to the development of psychiatric and neurological