Question

5. Describe the two most important concerns facing researchers in classifying primates. What are at least three advantages or disadvantages of cladistics and evolutionary taxonomy in resolving these issues?

Answer 1

ANSWER:

There are many issues with the current primate classification system. Many arise from the fact that there are primates that exhibit features from two classification groups.

• The classification groups may be changed to accommodate some of these issues, but often this creates even more problems. An example is the difficult-to-classify primate Goeldi’s monkey, which is sometimes classified with the marmosets and tamarins, and sometimes placed in a family on its own.
• Current primate classification reflects information from DNA analysis, which is often in conflict with traditional classifications based on anatomical features.

ADVANTAGE OF CLADISTICS CLASSIFICATION:

1. Using cladistics to classify organisms based on shared traits allows closely-related organisms to be grouped together which helps scientists study how they are related, what ancestors they have in common and how various characteristics evolved over time.
2. Cladistics is a more detailed classification system than basic biological taxonomy that considers only physical similarities between species.
3. Cladistics goes beyond this to incorporate quantitative measurements and puts emphasis on evolution and genealogy when comparing organisms. The data from cladistic analysis is used to create cladograms which are visual representations of the relationships between organisms.

DISADVANTAGE OF CLADISTICS:

Cladistic analysis is a popular method for reconstructing evolutionary relationships on the human lineage. However, it has limitations and hidden assumptions that are often not considered by palaeoanthropologists.

1. Some researchers who are opposed to its use regard cladistics as the preferred method for taxonomic "splitters" and claim it has lead to a revitalisation of typology. Typology remains a part of human evolutionary studies, regardless of the acceptance or use of cladistics. The assumption/preference for "splitting" over "lumping" in cladistics (alpha) taxonomy and the general failure to evaluate (post-hoc) such taxonomies have served to reinforce this assertion.
2. Researchers have also adopted a number of practices that are logically untenable or introduce considerable error. The evolutionary trend of human encephalisation, apparently isometric with body size, and concurrent reduction in the gut and masticatory apparatus, suggests continuous cladistic characters are biased by problems of body size. The method suffers a logical weakness, or circularity, leading to bias when characters with multiple states are used. Coding of such characters can only be done using prior criteria, and this is usually done using an existing phylogenetic scheme.
3. Another problem with coding character states is the handling of variation within species. While this form of variation is usually ignored by palaeoanthropologists, when characters are recognised as varying, their treatment as a separate state adds considerable error to cladograms. The genetic proximity of humans, chimpanzees and gorillas has important implications for cladistic analyses. It is argued that chimpanzees and gorillas should be treated as ingroup taxa and an alternative outgroup such as orangutans should be used, or an (hypothetical) ancestral body plan developed. Making chimpanzees and gorillas ingroup taxa would considerably enhance the biological utility of anthropological cladograms

ADVANTAGE OF EVOLUTIONARY TAXONOMY:

1. Evolutionary classification has 3 main advantages over the Linnaean system. First, Evolutionary classification tells you something important about the organism: its evolutionary history.
2. Second, Evolutionary classification does not attempt to "rank" organisms. Linnaean classification "ranks" groups of organisms artificially into kingdoms, phyla, orders, etc. This can be misleading as it seems to suggest that different groupings with the same rank are equivalent. For example, the cats (Felidae) and the orchids (Orchidaceae) are both family level groups in Linnaean classification. However, the two groups are not comparable:
3. Unique name for each species eliminates confusion, recognized around the world common language)

Disadvantage of Evolutionary classification

1. In Evolutionary trees, branches do not usually account for length of time. They depict evolutionary order and evolutionary difference. Evolutionary trees do not simply grow in only one direction after two lineages diverge; the evolution of one organism does not necessarily signify the evolutionary end of another.
2. Based on physical traits, physically similar species may not be related
3. Doesn't you molrecular evidence