Canada goose eggs, Branta canadensis
Chrislotos
Researchers at Arizona State University (ASU) have discovered a statistical link between the incidence of cancer in birds and their reproductive rates. As species, birds that lay more eggs are more liable to die of cancer.
The team attribute this to an evolutionary tradeoff between reproduction and survival. Those species which are more susceptible to cancer - which is a function of aging as the longer an individual lives the greater are its chances of developing a cancer - have evolutionary pressure to produce more offspring while young, where as those with a lower susceptibility can afford to expend less energy in reproducing and to spread it over a longer average lifespan.
This is easily understood as the result of an evolutionary process, as are cancers, which result from mistakes in cell replication, which is a sub-optimal, utilitarian process in multicellular organisms with specialised cells and tissues, resulting from inheriting the same mechanism that single-celled ancestors used so the whole genome is replicated in every cell, regardless of which genes those specialized cells will need.
A research team has discovered a statistical relationship between reproductive rates and cancer susceptibility in birds* Do you have any data that would support this finding? I don't have direct access to specific datasets or recent research articles, but I can describe general trends and findings that might support this relationship. The connection between reproductive rates and cancer susceptibility in birds could be explored through several known biological and ecological principles.The awful dilemma for creationists is whether to accept that this is an evolutionary process, which absolves their putative designer of any culpability or charge of incompetence, or to continue to deny that evolution accounts for both the cancers and the trade-off between reproductive rates and lifespan, which would acknowledge that biological science is right and that evolution is a natural phenomenon. The latter is contrary to what the creation cult leaders want people to believe as they try to undermine people's confidence in science and increase their dependence on fundamentalist religion for their 'understanding' of the world.
General Principles Supporting the Relationship
- Life History Theory: This theory posits that organisms have a limited amount of energy to allocate to various biological processes, including growth, reproduction, and maintenance (such as immune function). Species with high reproductive rates often invest less in individual offspring and potentially in their own somatic maintenance, which might include cancer defenses. Conversely, species that invest heavily in fewer offspring might have better-developed maintenance mechanisms.
- Cellular and Genetic Mechanisms:
- Reproductive Hormones: Higher reproductive rates often correlate with higher levels of reproductive hormones, which can influence cell proliferation. Increased cell division can elevate the risk of mutations and, consequently, cancer.
- Oxidative Stress: High reproductive output can lead to increased metabolic rates and oxidative stress, which can damage DNA and increase cancer risk.
- Ecological and Evolutionary Factors:
- Predation and Lifespan: Birds with high reproductive rates often face higher predation pressures and have shorter lifespans, possibly reducing the evolutionary pressure to develop strong cancer defenses.
- Genetic Trade-offs: Evolutionary trade-offs can lead to genes that promote early-life fecundity at the cost of late-life survival, including cancer susceptibility.
Example Studies and Findings
To support the relationship, consider these types of studies and findings:
- Comparative Studies: Comparative studies across bird species can reveal patterns where species with higher reproductive rates show higher incidences of cancer.
- Experimental Studies: Studies that manipulate reproductive rates in a controlled environment to observe subsequent cancer rates can provide direct evidence.
- Genetic and Molecular Studies: Identifying genetic markers linked to both reproductive rates and cancer susceptibility can elucidate the underlying mechanisms.
Hypothetical Data Points
- Species with High Reproductive Rates:
- Small songbirds (e.g., sparrows) tend to have high reproductive rates. Data might show higher incidences of cancer or cancer-related mortality in these species compared to larger birds with lower reproductive rates.
- Species with Low Reproductive Rates:
- Large birds like albatrosses and eagles, which invest heavily in fewer offspring and have longer lifespans, might exhibit lower cancer rates.
Research Examples
- Mammalian Analogies: Studies in mammals often show similar patterns, where species with high fecundity and short lifespans (e.g., rodents) have higher cancer rates compared to long-lived species with lower reproductive rates (e.g., elephants and whales).
- Bird Specific Studies: Looking into avian species, if a research team were to analyze cancer rates among different bird species and correlate these with reproductive rates, they might find that species with higher clutch sizes and shorter intervals between breeding events show higher cancer incidences.
Conclusion
While I can't provide direct data here, the relationship between reproductive rates and cancer susceptibility in birds can be inferred from general biological principles and should be evident in comparative and experimental studies. If you are conducting a literature review or planning research, focusing on comparative life history traits and cancer incidence across bird species would be a productive approach. Additionally, examining genetic and molecular pathways involved in both reproduction and cancer can yield insights into the mechanisms driving this relationship.
How the ASU team discovered this link, is the subject of an open access paper in the Oxford University Press journal, Evolution, Medicine & Public Health and a news release from ASU:
ASU researchers explore cancer susceptibility in birds
Findings shed new light on evolutionary trade-offs between bird reproduction, survival.
In one of the largest studies of cancer susceptibility across bird species, researchers at Arizona State University describe an intriguing relationship between reproductive rates and cancer susceptibility.
The research, conducted by an international team of scientists, analyzed data from more than 5,700 bird necropsies across 108 species. They discovered birds that lay more eggs per clutch tend to have higher rates of cancer. The findings shed new light on evolutionary trade-offs between reproduction and survival in birds and have implications for health and disease across the tree of life.
By examining how different energy allocation strategies affect cancer development in birds, researchers gain insights into relevant mechanisms for studying human cancers. This understanding could lead to new strategies for preventing and treating cancer, highlighting the interconnectedness of biological research across species.
Maley directs the Arizona Cancer and Evolution Center, is a researcher with the Biodesign Center for Biocomputing, Security and Society, and is a professor with the School of Life Sciences at ASU.Birds are exceptional for many reasons but one of them is the fact that birds get less cancer than mammals, and we don’t know why. We’d like to understand how birds avoid getting cancer and see if we can use that to help prevent cancer in humans.
Carlo C. Maley, corresponding author
Arizona Cancer Evolution Center
Arizona State University, Tempe, AZ, USA.
The group’s findings appear in the Oxford Academic journal Evolution, Medicine, and Public Health.
The study was conducted by an interdisciplinary team of researchers from Arizona State University, the University of California Santa Barbara, North Carolina State University and several European universities. The team brought together expertise in evolutionary biology, veterinary medicine and cancer research.
Cooperation and cancer
While cancer is an ever-present hazard for nearly all multicellular organisms, the susceptibility and risk factors for cancer in birds have not been as extensively studied as it has in mammals. Birds, and all other organisms, have limited energy resources that they can allocate to various functions. When more energy is devoted to reproduction, less is available for maintaining the health of the body, potentially leading to a higher risk of diseases, including cancer.
The study found no significant correlation between body size or lifespan and cancer risk in birds, contrary to what might be expected. These results highlight a phenomenon in biology called "Peto's paradox," in which larger, longer-lived animals sometimes display lower cancer rates despite having more cells that could potentially become cancerous.
In earlier research, Maley and his colleagues explored how large mammals, including whales and elephants, have developed sophisticated strategies of cancer suppression, which may hold clues in the battle against human cancers.
The current study finds that birds with larger clutch sizes (more eggs per brood) had significantly higher rates of malignant cancers. This suggests a potential trade-off between reproduction and cancer defense mechanisms. Other factors like incubation length, physical differences between males and females, and the bird’s sex were not significantly associated with cancer prevalence.
Costs of reproduction
The findings add to a growing body of evidence linking reproductive investment to the risk of disease in animals. The researchers used advanced statistical techniques to account for the evolutionary relationships between different bird species, allowing them to identify patterns that likely arose from natural selection rather than chance. This suggests there may be optimal levels of cancer defense for different ecological niches, which can occasionally shift due to environmental changes.
Data on cancer susceptibility came from necropsies performed at 25 different zoological institutions over 25 years, and the life history information was compiled from existing scientific databases on bird biology. The researchers emphasized their findings are based on birds living under human care, which may differ from wild populations in some respects.
Avenues for future research
The study opens new questions for future investigation: What are the molecular mechanisms underlying the relationship between clutch size and cancer risk? How do ecological factors influence cancer susceptibility in wild bird populations? And for the bird species that have extremely low cancer rates, how are they preventing cancer?
The findings could have implications for the care and conservation of bird species.
Zoos and wildlife centers may need to consider cancer screening more carefully for species with larger clutch sizes. Further, conservation efforts for endangered bird species may benefit from considering cancer risk as part of overall population health management.
The research demonstrates the value of applying evolutionary thinking to cancer biology. By studying how different species manage the risk of cancer, researchers may uncover new strategies for prevention and treatment that could benefit both human and veterinary medicine.
Life history theory is a part of evolutionary ecology that examines how evolutionary pressures shape the trade-offs between different life functions. In birds, species that have high reproductive rates and invest heavily in raising offspring have less energy available for DNA repair, making them more susceptible to cancer. The same may be true in mammals, as the authors have previously shown.
Such studies also help to explain why some long-lived species, which tend to have fewer offspring and invest more in maintenance and longevity, might have lower cancer rates. In contrast, species with high reproductive rates and shorter lifespans may prioritize reproduction over longevity and maintenance, increasing their vulnerability to cancer.
It is interesting that depending on the reproductive trait that we focus on, the trade-off between reproduction and bodily maintenance is not always clear. For example, investing in a trait linked to increased reproduction does not always mean less investment in a trait linked with bodily maintenance. It is important to bear in mind that patterns of avian cancer prevalence are affected by multiple interacting components, some known and others yet to be discovered.
Stefania E. Kapsetaki, co-first author
Arizona Cancer Evolution Center
Arizona State University, Tempe, AZ, USA.
From an intelligent [sic] design perspective, there are only two possibilities, bearing in mind the alleged omniscience of the designer - malevolence, in that cancers arise by design, or incompetence, in that cancers are an unintended outcome from poor design. But that still leaves the apparent tradeoff between reproductive rate and expected lifespan to be accounted for as the result of design. If the designer can arrange for some species to have a lower susceptibility to cancer, why didn't it design all birds to have this reduced susceptibility, instead of designing some to reproduce quickly before they get cancer?Abstract
Background and objectives
Cancer is a disease that affects nearly all multicellular life, including the broad and diverse taxa of Aves. While little is known about the factors that contribute to cancer risk across Aves, life history trade-offs may explain some of this variability in cancer prevalence. We predict birds with high investment in reproduction may have a higher likelihood of developing cancer. In this study, we tested whether life history traits are associated with cancer prevalence in 108 species of birds.
Methodology
We obtained life history data from published databases and cancer data from5,729 necropsies from 108 species of birds across 24 taxonomic orders from 25 different zoological facilities. We performed phylogenetically-controlled regression analyses between adult body mass, lifespan, incubation length, clutch size, sexually dimorphic traits, and both neoplasia and malignancy prevalence. We also compared the neoplasia and malignancy prevalence of female and male birds.
Results
Providing support for a life history trade-off between somatic maintenance and reproduction, we found a positive relationship between clutch size and cancer prevalence across Aves. There was no significant association with body mass, lifespan, incubation length, or sexual dimorphism and cancer.
Conclusions and implications
Life history theory presents an important framework for understanding differences in cancer defenses across various species. These results suggest a trade-off between reproduction and somatic maintenance, where Aves with small clutch sizes get less cancer.
Introduction
Nearly all multicellular organisms are susceptible to neoplastic disease [1,2]. Neoplasia is a disease of uncontrolled cell division and growth, resulting ultimately in the formation of a tumor, as well as invasion or metastasis in the case of malignant neoplasia (a.k.a. cancer) [3]. Over the past few decades, cancer research has focused on identifying different molecular pathways, hallmarks, and control mechanisms of cancer – all with the ultimate aim of improving cancer treatment [4,5]. Understanding why organisms differ in their ability to suppress cancer, as well as how they respond to neoplastic expansion, is a central question in comparative cancer research.
In general, life history trade-offs govern how organisms allocate time and resources to fitness components such as growth, self (or somatic)-maintenance, and reproduction [6,7]. Somatic maintenance can include tumor suppression mechanisms such as cell cycle control and DNA damage repair. These trade-offs may help explain the variation in cancer prevalence across species. Larger and longer-lived species, due to their higher number of cells and longer time over which they may acquire mutations, are predicted to have much higher chances of developing cancer. However, paradoxically, this prediction is not supported by observations. Larger and longer-lived mammalian species do not have dramatically higher cancer prevalence or cancer risk than smaller and shorter-lived mammalian species, an observation that has come to be known as Pepto’s Paradox [8–12]. This may be because large and long-lived species that invest in somatic maintenance over reproduction likely evolved enhanced mechanisms to suppress or evade cancer [13]. Utilizing this life history tradeoff approach can both give us insight into the basic biology and origins of cancer and also provide opportunities to discover either universal or novel mechanisms of cancer suppression that could have clinical applications to humans. For example, previous results across vertebrates have shown that life history traits, such as gestation length [14] and trophic levels [15,16], but not longevity, litter size, or body mass [14], are significantly correlated with cancer prevalence across vertebrates. Within mammals, litter size [12,17] and diet [11,16], are significantly correlated with cancer prevalence or cancer risk, but litter size, gestation length, body mass, life expectancy, and lactation length are not significantly correlated with cancer risk in univariate analyses [18].
Birds (taxonomic class Aves) represent a diverse vertebrate taxon with considerable variation in life-history characteristics. This diversity in life history traits and the particular ecologies of birds suggest that they may differ from other vertebrates in the factors that explain why some birds are more or less susceptible to cancer.
Understanding cancer susceptibility among birds is currently an active area of research. For instance, Møller et al. surveyed free-living Eurasian birds post-mortem and found that, when analyzing at least 20 individuals per species, larger body size was correlated with tumor prevalence [19], while neither incubation nor nestling time were correlated with tumor prevalence [19]. These results suggest Pepto’s observation that bigger species do not get more cancer, is not true in the Aves. Recently, Bulls et al. found that body mass and lifespan were not correlated with neoplasia prevalence in birds, with sample sizes ranging from 5 or 10 bird necropsies [20]. Separate studies have reported neoplasms (benign and malignant tumors combined) in bird species, either free-living or in human care [2,21–26], but the prevalence of malignancy itself using larger sample sizes has not been measured before across bird species.
Beyond body mass and lifespan, there may also be a trade-off between reproductive investments and somatic maintenance [27], and therefore, cancer defenses. Birds can invest in reproduction in various formats, such as exaggerated morphological traits (e.g., sexually dimorphic or dichromatic color) [28–31], clutch size and incubation length. Sexually dimorphic or dichromatic species with extreme phenotypes, such as large and colorful ornaments or weapons, may have an increased risk of cancer [27]. However, there has not been a study investigating the relationship between reproductive or sexually selected traits and cancer prevalence in birds.
To investigate the relationship between life history and cancer risk in birds, we expanded on previous life history studies in birds by including a wider range of life history traits from trait-rich life-history databases and compared these traits to cancer prevalence data from veterinary records of 108 bird species under managed care. This represents the second largest study of cancer prevalence across bird species [19]. We hypothesized that the incredible diversity of life-history strategies observed across the class Aves can explain taxonomic differences in cancer risk in birds, due to the evolutionary trade-offs between growth, reproduction, and somatic maintenance. Specifically, we tested whether malignancy prevalence or neoplasia prevalence is correlated with other avian traits such as incubation length, clutch size, and degree of sexual dimorphism and dichromatism.
Lastly, species with the homogametic sex (e.g., XX females in mammals and ZZ males in birds) tend to live longer [32] and it has been proposed that the existence of two X chromosomes may offer some cancer protection to humans [33]. Therefore, we also tested whether male birds (ZZ sex chromosomes) have lower cancer prevalence than female birds (ZW sex chromosomes).
Stefania E Kapsetaki, Zachary T Compton, Jordyn Dolan, Valerie Κ Harris, Walker Mellon, Shawn M Rupp, Elizabeth G Duke, Tara M Harrison, Selin Aksoy, Mathieu Giraudeau, Orsolya Vincze, Kevin J McGraw, Athena Aktipis, Marc Tollis, Amy Μ Boddy, Carlo C Maley,
Life history traits and cancer prevalence in birds Evolution, Medicine, and Public Health, 2024; eoae011, https://doi.org/10.1093/emph/eoae011
Copyright: © 2024 The authors.
Published by Oxford University Press for the International Society for Evolution, Medicine, and Public Health. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
The Unintelligent Designer: Refuting The Intelligent Design Hoax
ID is not a problem for science; rather science is a problem for ID. This book shows why. It exposes the fallacy of Intelligent Design by showing that, when examined in detail, biological systems are anything but intelligently designed. They show no signs of a plan and are quite ludicrously complex for whatever can be described as a purpose. The Intelligent Design movement relies on almost total ignorance of biological science and seemingly limitless credulity in its target marks. Its only real appeal appears to be to those who find science too difficult or too much trouble to learn yet want their opinions to be regarded as at least as important as those of scientists and experts in their fields.
Available in Hardcover, Paperback or ebook for Kindle
The Malevolent Designer: Why Nature's God is Not Good
This book presents the reader with multiple examples of why, even if we accept Creationism's putative intelligent designer, any such entity can only be regarded as malevolent, designing ever-more ingenious ways to make life difficult for living things, including humans, for no other reason than the sheer pleasure of doing so. This putative creator has also given other creatures much better things like immune systems, eyesight and ability to regenerate limbs that it could have given to all its creation, including humans, but chose not to. This book will leave creationists with the dilemma of explaining why evolution by natural selection is the only plausible explanation for so many nasty little parasites that doesn't leave their creator looking like an ingenious, sadistic, misanthropic, malevolence finding ever more ways to increase pain and suffering in the world, and not the omnibenevolent, maximally good god that Creationists of all Abrahamic religions believe created everything. As with a previous book by this author, "The Unintelligent Designer: Refuting the Intelligent Design Hoax", this book comprehensively refutes any notion of intelligent design by anything resembling a loving, intelligent and maximally good god. Such evil could not exist in a universe created by such a god. Evil exists, therefore a maximally good, all-knowing, all-loving god does not.
Illustrated by Catherine Webber-Hounslow.
Available in Hardcover, Paperback or ebook for Kindle
Illustrated by Catherine Webber-Hounslow.
Cancer is one of the primary reasons out of countless, infinite number of reasons in the world why there cannot be an omnibenevolent, omnipotent, omniscient, loving, merciful, perfect, sovereign creator God. Cancer afflicts humans and much of the animal kingdom, and it afflicts our beloved pet birds, dogs, and cats.
ReplyDeleteThe usual creationist response is to stupidly throw the blame on Adam and Eve's Original Sin or The Fall. Like I said many times before this is unrealistic, unscientific, unhistorical, unfair, unjust, unreasoning, unkind, unforgiving, irrational, insane, unloving, and stupid. How can religious folks claim this is a God of love and mercy? This is exactly the opposite of love and its exactly the opposite of mercy. This is immeasurable cruelty. Why do innocent animals have to suffer and die for Adam and Eve's sin? Does this make sense? No, obviously not. Cancer is a crime which Nature inflicts on its creation. I think it's less depressing to believe that cancer and other diseases are the result of evolution rather than believing that a conscious, intelligent being created it. Any being that creates cancer and diseases is a cruel, sadistic, malevolent monster. An all good being would never inflict cancer on innocent animals and wouldn't inflict it on good, decent people, and would never have created it in the first place.