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Open Access Publications from the University of California


The Journal of Evolution and Health brings together academic researchers and clinical practitioners to develop evolutionary insights into the major factors affecting health, and to translate those insights into practical methods for improving human and animal health.

Research Articles

Feasibility of a Web-Based Cross-Over Paleolithic Diet Intervention in the General Population

Introduction: The primary aim was to investigate feasibility of a web-based cross-over Paleolithic diet intervention in the general population. The secondary aim was to calculate the sample size needed to reach a statistically significant difference in effect of a Paleolithic-like diet on psychological and somatic symptoms compared with the Dutch consensus diet.

Methods: 35 participants from the general population were recruited using social media. Participants filled-out an intake questionnaire to assess representativeness of the sample. Participants were instructed to consume both a Paleolithic-like diet and the Dutch consensus diet during four weeks, the order was randomly assigned. After each period, participants filled-out a questionnaire to assess compliance to the dietary instructions, the Depression Anxiety Stress Scale to assess psychological symptoms and the Rosmalen Somatization Index to assess somatic symptoms.

Results: It took 42 days to recruit 35 participants, the drop-out rate was 20% and compliance to the diets was at least 68%. Participants were representative of the general Dutch population regarding age, BMI, marital and work status and symptoms of depression and anxiety. Participants showed greater reductions in psychological and somatic symptoms when consuming a Paleolithic-like diet compared to the Dutch consensus diet. Sample size calculations showed that at least 30 participants need to be recruited for statistical significance.

Conclusion: Conducting a web-based cross-over dietary intervention in the general population appeared feasible. Given the ease of increasing sample size in web-based studies, we recommend recruiting more participants than estimated when comparing a Paleolithic-like diet to the Dutch consensus diet.

Bacterial development of resistance to botanical antimicrobials

In recent years, increased numbers of multidrug-resistant strains of bacteria have opportunistically and selectively expanded while the pharmaceutical discovery of new antimicrobial therapies has been lacking to combat this growing threat. Like traditional antibiotics, botanicals have historically been used to treat bacterial infections, but it remains unclear if bacteria may have the capability to develop resistance to these therapeutic botanicals. It is believed that one advantage that may prevent or slow resistance to botanical antimicrobials is the presumed presence of the multiple endogenous substances contained within a plant that may act synergistically to inhibit microbial growth. This study examined the potential of an antimicrobial-sensitive strain of Staphylococcus aureus to develop resistance to five botanical extracts commonly used for antibacterial therapy. Our results demonstrated that S. aureus was able to develop resistance to the botanical antimicrobial extracts at a similar rate and level as standard antibiotics thus questioning the idea of multiple synergistic antimicrobials within a botanical tincture. These results demonstrate the need for proper use of botanical antimicrobial extracts to avoid the development of resistance to botanical-based therapeutics and avoid similar problems currently faced with pharmaceutical antibiotics.

Brace yourselves, winter is coming: a pilot study of the effects of brief, infrequent cold water immersion upon body composition in young adult males

Background: The existence of functioning brown adipose tissue (BAT) in adult humans has brought into question the possibility of utilising the BAT mechanism as an obesity tackling strategy. This pilot study examined the effects of a short-term (6wk) cold water immersion (CWI) programme on the body composition of (n=10) healthy male adults. It was hypothesized that the thermal stresses would produce reductions in fat mass (FM) and body fat percentage (BFp) as a result of thermogenic activation of the BAT mechanism. Methods: Using a single arm prospective trial design, participants were subjected to singular acute (18min) cold water exposures (15±1°C) weekly for the duration of the intervention (6wk). Results: Non-significant decreases were observed in FM (-1.55±2.24kg; p = 0.057) and BFp (-1.62±2.46%; p = 0.067), and significant increases in fat free mass (FFM; 1.46±1.68kg; p = 0.023). Conclusions: The results indicate that the intervention could be adopted as a plausible method to exert positive changes to body composition. These findings should stimulate follow up studies to examine the interventions efficacy in a larger more representative sample and examine its feasibility of implementation as a genuine obesity tackling strategy.

Psychological Outcomes Associated with CrossFit

CrossFit is an exercise program that was theoretically designed to map onto ancestral forms of exercise and movement. Whether CrossFit actually matches the kinds of movements that were regularly implemented by our pre-Agrarian ancestors is up for debate. Assuming that CrossFit, regardless of its actual evolutionary relevance, may have some benefits, the current work examined whether CrossFit is associated with psychological and social benefits to individuals compared with a more traditional exercise regimen (Gold’s Gym). This study included 188 participants, 69 Gold’s Gym members and 119 CrossFit members who completed an online survey. In addition to several questions about their perceptions of their workout experience, this survey asked them to describe their motivations for exercising. They also completed measures of the Big Five personality traits and several demographic measures (such as an index of socioeconomic status (SES)). Results demonstrated that people who attend the two different gyms do not differ from one another on average in terms of SES or basic personality structure. However, those who attended CrossFit emerged as reporting relatively positively in terms of such outcomes as experiencing challenge, obtaining social recognition, and forming affiliative bonds with others. Findings suggested that CrossFit members show higher levels of intrinsic motivation for their exercise regimen compared with those who attend Gold’s Gym. The implications for designing effective exercise regimens are discussed.

Clinical Article

The paleolithic ketogenic diet may ensure adequate serum magnesium levels


Magnesium plays an essential role in several enzymatic reactions. Its deficiency is known to be widespread and has been associated with a variety of pathological conditions characterized by chronic inflammation and/or oxidative stress. The connection between the metabolism of glucose and magnesium at the cell level is well-established. We hypothesize that magnesium deficiency in chronic conditions is primarily due to Western type carbohydrate based metabolism. In previous case studies we have shown that magnesium levels are normal on the paleolithic ketogenic diet. Here we assessed magnesium levels in a larger sample (n=50) to address whether the paleolithic ketogenic diet is able to ensure normal blood magnesium levels.

Materials and Methods

To assess magnesium levels in patients and healthy controls on the paleolithic ketogenic diet in a larger sample, we retrospectively analysed laboratory data obtained from 50 patients/subjects who were following the diet and were also not taking magnesium or other supplements. Correlation calculation was performed between magnesium and glucose levels.


We found magnesium levels to be in the normal range in all but one patient/subject. There was a significant inverse correlation between glucose and magnesium levels.


Our results indicate that the paleolithic ketogenic diet ensures normal magnesium levels in various pathological conditions as well as in healthy subjects. We believe that the high prevelance of magnesium deficiency reported earlier for a variety of chronic conditions is correlated with carbohydrate-based Western type nutrition rather than that of the chronic condition itself. We discuss underlying mechanisms.

Popular Article

Proceedings of the 5th annual symposium of the German Society for Paleo Nutrition held in 2017

We present the scientific abstracts of the 5th Annual Symposium of the German Society for Paleo Nutrition (Deutsche Gesellschaft für Paläoernährung) which took place on September 23rd 2017 in Giessen, Germany.

Besides an overview on existing interventional studies on Paleolithic diets, a focus of this year´s symposium was on secondary plant metabolites: presence, standardization by phytoneering and the role of phytomedicine for prevention and treatment of cancer. Further topics were the role of vitamin-D and omega-3 fatty acids, as well as molecular anthropology and personalized nutrition.


An evolutionary hypothesis to explain the role of deconditioning in low back pain prevalence in humans


The aim of the present piece is to present an evolutionary hypothesis relating to the role of deconditioning in the prevalence of low back pain (LBP) in humans. LBP is a multifactorial issue with many associated symptoms and potential causes. Prevalence is high in westernised populations and also rural and indigenous populations. Other diseases common in western populations, such as obesity, diabetes, heart disease, and cancer are almost absent in populations devoid of western influence who follow a traditional diet and lifestyle. It therefore seems counter-intuitive that LBP should also be high in traditional populations. The hypothesis that an evolutionarily determined factor might predispose LBP across a wide range of Homo sapiens populations seems plausible to examine. Fossil data from the infra-order Anthropoidea suggest adaptations in predominant habitual locomotion styles from 1) arboreal quadruped, to 2) semi-terrestrial quadruped, to 3) biped over the past ~20 million years. These adaptations were accompanied and permitted by anatomical evolutionary changes occurring in the lumbar spine and pelvis including development from 1) a long mobile lumbar vertebral column, laterally facing pelvis and large lumbar extensors to 2) a short lumbar vertebral column, posterior location of the transverse process, lengthening of the ilia, general reduction of the lumbar extensor musculature and increase in passive rigidity through entrapment and invagination and 3) to re-lengthening of the vertebral column, reduction in length and broadening of the ilia and sacrum. Comparative musculature anatomy between old world monkeys and modern humans suggests the presence of relatively smaller, and potentially weaker, lumbar extensor musculature in humans. Further, hip/trunk extensor musculature of short backed primates is well developed. Anatomically modern humans therefore may bear the compromise of relatively strong hip/trunk extensors and relatively weak lumbar extensors in combination with a long flexible lumbar spine. This may contribute to disuse atrophy of the lumbar extensors which may explain the consistent association of their deconditioning in LBP, and also predispose modern humans to the high prevalence of LBP presently observed.


A “Diagnosis Method" for the Analysis of Epidemiological Studies. A Reevaluation of Pan, et al. Arch Intern Med 2012, 172:555.

The medical literature has been subject to extensive criticism for a lack of accuracy and reproducibility. A major cause, in our view, is misleading or inappropriate presentation and interpretation of statistical results. Emphasis on percentages or relative values (odds ratios, relative risk, and hazard ratio) always reduces and often obscures information. We suggest a more direct method using the 2 x 2 matrix commonly employed in diagnosis testing. We demonstrate the “diagnosis method,” by evaluating a previously published paper (Pan A, et al.: Arch Intern Med 2012, 172:555-563). on the risk of red meat for disease, focussing on cancer risk. The direct analysis shows very small effects of red meat. Given the generally large errors in the independent variable measured by food frequency questionnaire, even this low predictability is likely to be unreliable. In combination with other studies in the literature, the analysis suggests that red meat is unlikely to be a risk for cancer. The major point is that statistical significance does not necessarily point to biological or clinical importance.