The father of natural immunity, as Siamon described him, is credited with the discovery that antimicrobial defence requires the specific recruitment of specialized cells, the phagocytes, which are able to kill and eat potential pathogens. The larger of these specialized cells in mammals, the macrophages or big eaters are the subject of this review. My interest in macrophages started during my PhD, which included a year spent at the Max Planck Institute for Immunobiology in Freiburg in the late s. This Institute was directed by its founder, Professor Otto Westphal, a pioneer in understanding the biochemistry of bacterial lipopolysaccharides LPSalso known as endotoxins, which initiate much of the pathology of septicaemia.
Max Gerber] I am often asked whether I agree with the new group selectionists, and the questioners are always surprised when I say I do not. After Bacterial morphology essay, group selection sounds like a reasonable extension of evolutionary theory and a plausible explanation of the social nature of humans.
Also, the group selectionists tend to declare victory, and write as if their theory has already superseded a narrow, reductionist dogma that selection acts only at the level of genes. In this essay, I'll explain why I think that this reasonableness is an illusion.
The more carefully you think about group selection, the less sense it makes, and the more poorly it fits the facts of human psychology and history. The problem is that it also obfuscates evolutionary theory by blurring genes, individuals, and groups as equivalent levels in a hierarchy of selectional units; Most importantly, it has placed blinkers on psychological understanding by Bacterial morphology essay many people into simply equating morality and culture with group selection, oblivious to alternatives that are theoretically deeper and empirically more realistic.
Does this mean that the human brain has been shaped by natural selection to promote the welfare of the group in competition with other groups, even when it damages the welfare of the person and his or her kin? If so, does the theory of natural selection have to be revamped to designate "groups" as units of selection, analogous to the role played in the theory by genes?
Several scientists whom I greatly respect have said so in prominent places. And they have gone on to use the theory of group selection to make eye-opening claims about the human condition. Wilson explains, "In a group, selfish individuals beat altruistic individuals.
But, groups of altruistic individuals beat groups of selfish individuals. They suggest that evolution has equipped humans to solve tragedies of the commons also known as collective action dilemmas and public goods gamesin which actions that benefit the individual may harm the community; familiar examples include overfishing, highway congestion, tax evasion, and carbon emissions.
And they have drawn normative moral and political conclusions from these scientific beliefs, such as that we should recognize the wisdom behind conservative values, like religiosity, patriotism, and puritanism, and that we should valorize a communitarian loyalty and sacrifice for the good of the group over an every-man-for-himself individualism.
I am often asked whether I agree with the new group selectionists, and the questioners are always surprised when I say I do not. Why does this matter? I'll try to show that it has everything to do with our best scientific understanding of the evolution of life and the evolution of human nature.
And though I won't take up the various moral and political colorings of the debate here I have discussed them elsewhereit ultimately matters for understanding how best to deal with the collective action problems facing our species.
The first big problem with group selection is that the term itself sows so much confusion. People invoke it to refer to many distinct phenomena, so casual users may literally not know what they are talking about. I have seen "group selection" used as a loose synonym for the evolution of organisms that live in groups, and for any competition among groups, such as human warfare.
Sometimes the term is needlessly used to refer to an individual trait that happens to be shared by the members of a group; as the evolutionary biologist George Williams noted,"a fleet herd of deer" is really just a herd of fleet deer. And sometimes the term is used as a way of redescribing the conventional gene-level theory of natural selection in different words: In this essay I'll concentrate on the sense of "group selection" as a version of natural selection which acts on groups in the same way that it acts on individual organisms, namely, to maximize their inclusive fitness alternatively, which acts on groups in the same way it acts on genes, namely to increase the number of copies that appear in the next generation; I will treat these formulations as equivalent.
Modern advocates of group selection don't deny that selection acts on individual organisms; they only wish to add that it acts on higher-level aggregates, particularly groups of organisms, as well.
For this reason, the theory is often called "multilevel selection" rather than "group selection.ADVERTISEMENTS: Essay on Bacteria! Contents: Meaning of Bacteria Characters of Bacteria Morphology of Bacteria Size of Bacteria and the Significance of their Being Small Flagellation in Bacteria Taxes (Behavioural Responses) Endospores Reproduction in Bacteria Some Important Bacterial Genera Essay # 1.
Meaning of Bacteria: . Since , CELLS alive! has provided students with a learning resource for cell biology, microbiology, immunology, and microscopy through the use of mobile-friendly interactive animations, video, puzzles, quizzes and study aids.
Peptidoglycan is the major component of the cell envelope of virtually all bacteria. It has structural roles and acts as a selective sieve for molecules from the outer environment. Peptidoglycan synthesis is therefore one of the most important biogenesis pathways in bacteria and has been studied.
View Essay - Task#2 from NURSING BS c at Western Governors University. Bacterial Morphology Experiment 1: Compare your observations from the four activities of fresh wet mount, direct staining85%(13).
Specific bacterial morphologies noted in exercise one come from the spiral bacteria sample. The shape appears to be corkscrew in nature and vary in length throughout the sample slide.
The length varies but the width seems to be uniform. THE FALSE ALLURE OF GROUP SELECTION. Human beings live in groups, are affected by the fortunes of their groups, and sometimes make sacrifices that benefit their groups.