The manual pressures of stone tool behaviors and their implications for the evolution of the human hand

Publication date: June 2018
Source:Journal of Human Evolution, Volume 119
Author(s): Erin Marie Williams-Hatala, Kevin G. Hatala, McKenzie Gordon, Alastair Key, Margaret Kasper, Tracy L. Kivell
It is widely agreed that biomechanical stresses imposed by stone tool behaviors influenced the evolution of the human hand. Though archaeological evidence suggests that early hominins participated in a variety of tool behaviors, it is unlikely that all behaviors equally influenced modern human hand anatomy. It is more probable that a behavior's likelihood of exerting a selective pressure was a weighted function of the magnitude of stresses associated with that behavior, the benefits received from it, and the amount of time spent performing it. Based on this premise, we focused on the first part of that equation and evaluated magnitudes of stresses associated with stone tool behaviors thought to have been commonly practiced by early hominins, to determine which placed the greatest loads on the digits. Manual pressure data were gathered from 39 human subjects using a Novel Pliance^® manual pressure system while they participated in multiple Plio-Pleistocene tool behaviors: nut-cracking, marrow acquisition with a hammerstone, flake production with a hammerstone, and handaxe and flake use. Manual pressure distributions varied significantly according to behavior, though there was a tendency for regions of the hand subject to the lowest pressures (e.g., proximal phalanges) to be affected less by behavior type. Hammerstone use during marrow acquisition and flake production consistently placed the greatest loads on the digits collectively, on each digit and on each phalanx. Our results suggest that, based solely on the magnitudes of stresses, hammerstone use during marrow acquisition and flake production are the most likely of the assessed behaviors to have influenced the anatomical and functional evolution of the human hand.



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Kanapoi revisited: Paleoecological and biogeographical inferences from the fossil fish

Publication date: Available online 27 March 2018
Source:Journal of Human Evolution
Author(s): Kathlyn M. Stewart, Scott J. Rufolo
Fish fossils were recovered from three different depositional contexts at the Pliocene Kanapoi site to: 1) test the assumption that habitat and ecology of modern fish taxa can predict habitat and ecology of fossil taxa; 2) reconstruct the lake and river environments in the Kanapoi Formation, with reference to fish fossils from the nearby Lothagam site deposits; and 3) investigate biogeographical inferences from the fossils. We compare the Kanapoi fish taxa and their depositional environments with the taxa and environments in modern Lake Turkana, and with another Plio-Pleistocene fauna from the eastern Turkana Basin. Taphonomic caveats are discussed. Our results support the use of ecological preferences of modern fish to predict past preferences. Our analysis of the Kanapoi fossils also indicates that the Pliocene Lonyumun Lake had a diverse fauna, with an unusual mix of taxa compared to the modern lake. The presence of possibly endemic species in the Pliocene lake may additionally represent a period of isolation during this epoch. Few fish fossils were recovered in the deposits of the ancestral Kerio River, a primary affluent of Lonyumun Lake then as now, but those present indicate a different ecology than that interpreted for the modern lake. Previously unknown fish taxa which enter the lake during the Pliocene suggest the existence of a connection between the Nile River and the Turkana Basin, which may have been viable for other vertebrates, including hominins.



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The Importance of the Saphenous Nerve Block for Analgesia Following Major Ankle Surgery: A Randomized, Controlled, Double-Blind Study

Background and Objectives Major ankle surgery causes intense postoperative pain, and whereas the importance of a sciatic nerve block is well established, the clinical significance of a supplemental saphenous nerve block has never been determined in a prospective, randomized, double-blind, placebo-controlled trial. We hypothesized that a saphenous nerve block reduces the proportion of patients experiencing significant clinical pain after major ankle surgery. Methods Eighteen patients were enrolled and received a popliteal sciatic nerve block. Patients were randomized to single-injection saphenous nerve block with 10 mL 0.5% bupivacaine with 1:200,000 epinephrine or 10 mL saline (Fig. 1). Primary outcome was the proportion of patients reporting significant clinical pain, defined as a score greater than 3 on the numerical rating scale. Secondary outcomes were maximal pain and analgesia of the cutaneous territory of the infrapatellar branch of the saphenous nerve. Results Eight of 9 patients in the placebo group reported significant clinical pain versus 1 of 9 patients in the bupivacaine-epinephrine group (P = 0.003). Maximal pain was significantly lower in the active compared with the placebo group (median, 0 [0–0] vs 5 [4–6]; P = 0.001). Breakthrough pain from the saphenous territory began within 30 minutes after surgery in all cases. Sensory testing of the cutaneous territory of the infrapatellar branch of the saphenous nerve showed correlation between pain reported in the anteromedial ankle region and the intensity of cutaneous sensory block in the anteromedial knee region. Conclusions The saphenous nerve is an important contributor to postoperative pain after major ankle surgery, with significant clinical pain appearing within 30 minutes after surgery. Clinical Trials Registration This study has been registered at ClinicalTrials.gov, identifier NCT02697955. Accepted for publication November 20, 2017. Address correspondence to: Thomas Fichtner Bendtsen, MD, PhD, Department of Anesthesiology and Intensive Care Medicine, Aarhus University Hospital, Noerrebrogade 44, DK-8000 Aarhus, Denmark (e-mail: tfb@dadlnet.dk). Funding was received from the A. P. Møller and Chastine Mc-Kinney Møller Foundation. The content is solely the responsibility of the authors. The authors declare no conflict of interest. Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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Too Deep or Not Too Deep?: A Propensity-Matched Comparison of the Analgesic Effects of a Superficial Versus Deep Serratus Fascial Plane Block for Ambulatory Breast Cancer Surgery

Background and Objectives Serratus fascial plane block can reduce pain following breast surgery, but the question of whether to inject the local anesthetic superficial or deep to the serratus muscle has not been answered. This cohort study compares the analgesic benefits of superficial versus deep serratus plane blocks in ambulatory breast cancer surgery patients at Women's College Hospital between February 2014 and December 2016. We tested the joint hypothesis that deep serratus block is noninferior to superficial serratus block for postoperative in-hospital (pre-discharge) opioid consumption and pain severity. Methods One hundred sixty-six patients were propensity matched among 2 groups (83/group): superficial and deep serratus blocks. The cohort was used to evaluate the effect of blocks on postoperative oral morphine equivalent consumption and area under the curve for rest pain scores. We considered deep serratus block to be noninferior to superficial serratus block if it were noninferior for both outcomes, within 15 mg morphine and 4 cm·h units margins. Other outcomes included intraoperative fentanyl requirements, time to first analgesic request, recovery room stay, and incidence of postoperative nausea and vomiting. Results Deep serratus block was associated with postoperative morphine consumption and pain scores area under the curve that were noninferior to those of the superficial serratus block. Intraoperative fentanyl requirements, time to first analgesic request, recovery room stay, and postoperative nausea and vomiting were not different between blocks. Conclusions The postoperative in-hospital analgesia associated with deep serratus block is as effective (within an acceptable margin) as superficial serratus block following ambulatory breast cancer surgery. These new findings are important to inform both current clinical practices and future prospective studies. Accepted for publication November 27, 2017. Address correspondence to: Faraj W. Abdallah, MD, The Ottawa Hospital General Campus, 501 Smyth Rd, Ottawa, Ontario, Canada K1H 8L6 (e-mail: FAbdallah@toh.ca). This work was supported by departmental funding. F.W.A. and R.B. are supported by the Merit Award Program, Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada. R.B. also receives research support from the Evelyn Bateman Cara Operations Endowed Chair in Ambulatory Anesthesia and Women's Health, Women's College Hospital, Toronto. The authors declare no conflict of interest. Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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What do randomized controlled trials say about virtual rehabilitation in stroke? A systematic literature review and meta-analysis of upper-limb and cognitive outcomes

Virtual-reality based rehabilitation (VR) shows potential as an engaging and effective way to improve upper-limb function and cognitive abilities following a stroke. However, an updated synthesis of the litera...

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The clinical relevance of advanced artificial feedback in the control of a multi-functional myoelectric prosthesis

To effectively replace the human hand, a prosthesis should seamlessly respond to user intentions but also convey sensory information back to the user. Restoration of sensory feedback is rated highly by the pro...

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EMT - Basic - First Response Ambulance

Emergency Medical Technicians-Basic (EMT-B) respond to emergency calls to provide efficient and immediate care to the critically ill and injured, and to transport the patient to a medical facility. After receiving the call from the dispatcher, the EMT-B drives the ambulance to address or location given, using the most expeditious route, depending on traffic and weather conditions. The EMT-B must observe ...

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