Introduction (~2/3 page): In this section you will introduce and provide background on the relationships between body mass, brain size, and life history variables. How are these variables related in humans, apes, and other primates? Hint: these relationships are shown in scatterplots in the Data Analysis worksheet for Lab 4. Refer to them as needed. How do humans compare to other apes in terms of encephalization quotient (EQ), age at first reproduction, and maximum lifespan? How do the fossil hominins compare to humans, apes, and other primates in these variables? Why might some of the hominins appear as outliers in these variables compared to other primates? Use the information provided to you in class support your claims. We will not be using outside literature in this final report!
In the final paragraph of the introduction you should introduce the particular project you did in lab. Scientific papers often begin this section with a statement such as “In this project, we investigated…” and then tell the reader what it is you investigated. For this lab you are investigating how and when the human-like pattern of large brains, long growth periods, and long maximum lifespans evolved by examining and estimating these traits in fossil hominins.
Methods (~1/2 page): In this section you should describe what you measured, how you collected it, and how the data were analyzed. Describe each trait that was measured, how the measurement was performed, and what tools were used (e.g. type of calipers). Be sure to include the units the data were collected in, the sample size, and specimens measured. In the second paragraph state how you analyzed you data and tested your predictions. Address how the measurements you collected were used to estimate body mass and calculate brain size for the specimens. Additionally, how were estimated body mass and brain size used to estimate life history variables and encephalization quotient?
Results (~1/3 page): In this section you should describe the results of your three hypotheses. Address at least the following: what did your data look like? How do the life history variables and EQ compare between the fossil hominins, humans, and other primates? Do your results support or challenge your hypotheses? Refer to the Figures to describe how the results look.
Discussion (~2/3 page): In this section you should discuss the impact of your results and how the results of this study relate to the larger issue of how and when the human-like pattern of large brains, long growth periods, and long maximum lifespans evolved in the hominin group. Briefly describe the relationship between body mass, life history, and brain size. How are humans unique in these traits compared to other primates? Did your results support or refute your hypotheses and why do you think you observed the patterns you found?
One major issue that all studies investigating fossil species must discuss is the dependence on estimates: we often cannot measure the variable we’re interested in (for example, we can’t observe an Australopithecus juvenile grow up and record when it reproduces for the first time). Instead, we estimate variables from skeletal measurements. Estimated variables should always be interpreted cautiously and critically. With that in mind, address at least the following: How do you interpret the life history estimates for fossil hominins in this study? Are they accurate, too high, or too low? Refer to the measures of EQ for these species: how can the relative brain size for the fossil hominins aid us in reconstructing their life histories? If there were any problems or limitations with the study, discuss those here.
