Ryan Hurley, Caitlin Marks, Hania Oleszak, Lindsay Stone, & Kyle Wyss

Transcription

1 Visuospatial integration and human evolution: the fossil evidence Bruner et al. Ryan Hurley, Caitlin Marks, Hania Oleszak, Lindsay Stone, & Kyle Wyss

2 Visuospatial Integration The ability to coordinate the inner and outer environments through the interface of the body. Extended Cognition = the brain body, and external objects work as a single unit to form the mind

3 The Body Interface & The Brain The Brain: ex: Parietal Lobe The Body Interface: ex: Teeth, Hands

4 Focus of Study Goal: Understand the evolution of the integration of the brain, body, and environment in humans Process: Evolutionary study of parietal lobe, hand, and teeth anatomy in extinct hominids

5 Neanderthal Vs Human Brains Bruner et al compared brains of Neanderthals and modern humans Found different sizes of parietal lobe

6 Brain Area Differences Humans-greater volume of parietal cortex Neanderthals-greater volume of occipital cortex Not seen in any other species, likely an automorphic trait

7 Effects of Parietal Bulging Parietal bulging in humans associated with early postnatal ontogenetic stage Bulging increased size of intraparietal sulcus, size of precuneus, and overall vascularity of parietal lobe

8 Cognitive Changes Parietal cortex involved with visuospatial integration-somatosensory (body) + occipital (vision) Precuneus-involved with internal representations, coordinating self, spatial awareness, self awareness

9 Dental anthropology Hominids use anterior teeth as a tool or third hand Stuff and cut technique Labial scratches Arranged obliquely and are visible to naked eye Studied in order to identify species-specific behaviors, cultural practices, as well as changes in both throughout evolution

10 Labial scratches in hominids

11 Labial Scratches In our species Lozano et al., Observed labial scratches on 31 Australian aborigines Marks only on 43% of individuals Average of one marks per tooth In hominids, presence of scratches was on 100% of individuals with an average of 44 marks per tooth Use of mouth as third hand is not necessary to develop a complex culture

12 Hand lateralization Homo heidelbergensis and Neanderthals prefered right oblique (10% showed left-handedness) Hand lateralization is strongly related to brain lateralization, which is associated with an ability in language

13 Hand Evolution We do not know early Homo hand anatomy - hard to classify into taxonomic groups Significant Findings: 1960s - remains of either Homo habilis or Paranthropus showed a lot of similarities to the human hand = modern grip shape of the articular facet between the trapezium and thumb flexor pollicis longus insertion is the same on the distal pollical phalanx

14 Hand Evolution Significant Findings (cont.): 1990s - Paranthropus were toolmakers and had modern hands 2010s - early Homo species had modern characteristics styloid process in a metacarpal that was 1.42 million years old = allows the hand to interlock with the wrist and thus can use complex tools

15 Hand Evolution 1 How we are different from extinct human species 3 (1)Reduced distal tuberosity in distal phalanges (2)Short distal pollical phalanx (3)Less broad trochleas in middle phalanges 2

16 Hand Evolution Neandertals and Modern Humans Neandertals are more robust in general, which suggests a difference in manipulative capabilities but this is speculative Found a modern hand dating 110,000 years ago Found Neandertal remains dating to 120,000 to 50,000 years ago at the same site Same tools but different anatomy

17 Evolution & Visuospatial Integration of visuospatial information allows manipulation of the world around us Functions include coordinating the brain, body and environment Scientists believe the evolution of this ability correlates with hominization of humanlike ancestors in our evolutionary tree, thanks to paleoanthropology

18 Paleoanthropology Definition: Study of the formation and development of humanlike characteristics (hominization) and the reconstruction of evolutionary relationships between hominids through the study of fossils Fossils could be skeletal remains, footprints, tools, etc.

19 Paleoanthropological Evidence & Visuospatial Integration Parietal Lobe Hand Dental Enlargement of areas for visuospatial organization Fossil evidence suggests evolution for complex tool use and interaction with our environment Scratches indicate tool use and hand lateralization (associated with brain lateralization)

20 Paleoanthropological Conclusions In hominids: anatomical change -> varying visuospatial ability -> cultural change All arises from integrating multiple sources of evidence Are these changes caused by genetic changes or environment-induced epigenetic factors? Still much left unanswered

21 sources