Research - Erik Otarola-Castillo

RESEARCH

C.V.

Erik Otárola-Castillo | RESEARCH

Optimal Foraging and Hunting Behavior in the genus Homo - How should evolutionary processes affect foraging behavior of organisms in the genus Homo? What behaviors should be expected under strong and weak selection? What do we actually observe?

In general human (Homo sapiens) foragers differ very little from many other foraging organisms. Natural selection has shaped their survival strategies. The latter include making decisions about how captured prey carcasses should be returned to their area of residence. Some often employ carriers or helpers to aid in returning the prey to camp. My goal here was to construct a model providing me with the the effects of fluctuating distances from the base camp and the number of carriers employed on the return rate of the transported load. View Larger Plot

Modeling Optimal Prey Part Transport by Homo sapiens Foragers- What is the transport probability of skeletal elements from a kill to a residential area? What other variables condition this probability?

Benjamin Schoville and I (in prep) provide a theoretical behaviorally-stochastic model against which inferences of transport strategies as a function of distance from a central place (and thereby, encounter rates) with large bovids may be tested.

Theoretical expectations from the transport model developed here can

The above plot shows the the "Types of Individual Parts" returned on the x-axis, the Number of Parts Returned on the y-axis. The variability in skeletal part transport at given distances from camp are provided by the flucutuating boxplots.

View Larger Plot

be useful to archaeologists and human ecologists interested in fluctuations in skeletal element representation attributed to human foraging.

Quantification of Early Homo sapiens Symbolism - Earliest remains assumed to constitute evidence of human symbolism date to ~77,000 years BP in southern Africa. Purported early symbolic artifacts include perforated shell-beads and intentionally engraved ochre tablets. However, do all engraved items necessarily carry symbolic meaning?

Benjamin Schoville, Janni Pederson and I asked this question and quickly realized that assesing if artifacts carried symbolic meaning to their makers is difficult at best.

We therefore developed a probabilistic method, based on randomization procedures, to assign confidence to our inferences regarding symbolism.

Using simulated data and the earliest engraved artifacts assumed to convey symbolic meaning, to test our method.

The plot to the left shows the randomization procedure under which our sample "ochre tablet engravings" were tested for meaning.

Reconstruction of Past Environments - Archaeologists need to infer the prehistoric ecological contexts within which prehistoric Homo sapiens foragers operated. However, this is often based on qualitative "interpretations" of the paleoecological record. Using fossil pollen community data, I conducted a quantitative paleoecological recostruction which will allow me to use space-time statistics to provide an estimated surface context to the Paleoindian archaeological record of the North American Great Plains. The plot below is my recent reconstruction of Great Plains Plaeoenvironment using ~2,000 fossil pollen communitry samples. Click on the image to view a larger illustration.

Modeling Processes Across Space - Foraging and habitat choice are undeniably closely tied to the availability and distribution of critical resources on the landscape. Quantitaively modeling the spatial dependence of said patterns provides a better understanding of the underlying processes that created them, and can further help us predict the processes' variability accross space. I currently have multiple projects dealing with space, including niche and paleoclimatic modeling through time. Click on images to view larger illustrations.

Quantifying Morphometric Variability - Analyses of projectile point shape and size provide information of functional and cultural properties between said artifctas. Geometric morphometrics (GM) isolates the shape and size of objects, therefore separating function and style. Moreover, the superior statistical properties of GM render it a more desireable methodology over traditional morphometric approaches.

Analysis of form allow archaeologists and anthropologists to organize artifacts based on their likeness and dissimilarities. In general archaeologist attempt to discriminate between the "function" and "style" of an artifact. In terms of projectile points, function is by and large related to size and its respective propelling technology. Stylistic differences in form on the other hand, reflect cultural sources of variation (see Boyd and Richerson 1985, 2005). Although projectile point functionality, interms of propelling technology can be measured by size, variation introduced by cultural sources continues to be diffcult to assess.

Geometric Morphometrics provides researchers with theoretically sound methodologies to separate and quantify the variation in both size and shape. Therefore also separating any functional variability attributed to size as well as stylistic variation inherent in culturally reproduced forms.

Potted Heather

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