Paleoparasitology (or "palaeoparasitology") is the study of parasites from the past, [2] and their interactions with hosts and vectors; it is a subfield of paleontology, the study of living organisms from the past. Some authors define this term more narrowly, as "Paleoparasitology is the study of parasites in archaeological material." (p. 103) [3] K.J. Reinhard suggests that the term "archaeoparasitology" be applied to "... all parasitological remains excavated from archaeological contexts ... derived from human activity" and that "the term 'paleoparasitology' be applied to studies of nonhuman, paleontological material." (p. 233) [4] This article follows Reinhard's suggestion and discusses the protozoan and animal parasites of non-human animals and plants from the past, while those from humans and our hominid ancestors are covered in archaeoparasitology.
The primary sources of paleoparasitological material include mummified tissues, [6] [5] [7] coprolites (fossilised dung) from mammals [8] or dinosaurs, [9] fossils, [10] and amber inclusions. [11] Hair, [12] skins, [13] and feathers [14] also yield ectoparasite remains. Some archaeological artifacts document the presence of animal parasites. One example is the depiction of what appear to be mites in the ear of a "hyaena-like" animal in a tomb painting from ancient Thebes. [15]
Some parasites leave marks or traces (ichnofossils) on host remains, which persist in the fossil record in the absence of structural remains of the parasite. Parasitic ichnofossils include plant remains which exhibit characteristic signs of parasitic insect infestation, such as galls or leaf mines [16] [17] [18] [19] and certain anomalies seen in invertebrate endoskeletal remains. [20] [21] [22] [23] [24] [25]
Plant and animal parasites have been found in samples from a broad spectrum of geological periods, including the Holocene (samples over 10,000 years old), [26] Pleistocene (over 550,000 years old), [27] Eocene (over 44 million years old), [28] Cretaceous (over 100 million years) [29] and even Lower Cambrian (over 500 million years). [30]
One of the most daunting tasks involved in studying parasitic relationships from the past is supporting the assertion that the relationship between two organisms is indeed parasitic. [31] Organisms living in "close association" with each other may exhibit one of several different types of trophic relationships, such as parasitism, mutualism, and commensalism. Demonstration of true parasitism between existing species typically involves observing the harmful effects of parasites on a presumed host. Experimental infection of the presumed host, followed by recovery of viable parasites from that host also supports any claim of true parasitism. Obviously such experiments are not possible with specimens of extinct organisms found in paleontological contexts.
Assumptions of true parasitism in paleontological settings which are based on analogy to known present-day parasitic relationships may not be valid, due to host-specificity. For example, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense are both devastating human parasites, but the related subspecies Trypanosoma brucei brucei will infect a number of animal hosts, but cannot even survive in the human blood stream, much less reproduce and infect a human host. [32] So a related (or unidentifiable) species of Trypanosoma found in a paleontological or archaeological context may not be a true human parasite, even though it appears identical (or very similar) to the modern parasitic forms.
The most convincing evidence of paleoparasitism is obtained when a presumed parasite is found in direct association with its presumed host, in a context that is consistent with known host-parasite associations. Some examples include helminths caught in amber in the process of escaping from the body of an insect, [33] lice found in the fur of guinea pig mummies, [34] protozoans in the alimentary canal of flies in amber, [35] [36] nematode larvae found embedded in animal coprolites, [37] [38] and a mite caught in amber in the process of apparently feeding on a spider. [39] In 2023, nematode eggs and possibly protozoan cysts were found in the Late Triassic coprolite of phytosaur. [40] Some holes in the mandibles of several specimens of Tyrannosaurus may have been caused by Trichomonas -like parasites. [41]
Fossil organisms which are related to present-day parasites often possess the morphological features associated with a parasitic lifestyle, such as blood-feeding mouthparts. [42] So fossil ticks [43] [44] and hematophagous insects [45] are generally assumed to be ectoparasites, even when their remains are found in the absence of a host. The ancient flea Saurophthirus found in Early Cretaceous deposits had a sucking proboscis and a stretching abdomen, which indicates the parasitic lifestyle of this insect. [46] [1]
The presence of structures resembling leaf miner trails in leaf fossils provide indirect evidence of parasitism, even if remains of the parasite are not recovered. [47] The dramatic tissue aberrations seen in present-day plant galls and gall-like structures in some invertebrates are direct physiological reactions to the presence of either metazoan parasites or microbial pathogens. Similar structures seen in fossil plant [48] and invertebrate [49] remains are often interpreted as evidence of paleoparasitism.
Host-parasite interactions today are often exploited by other species, and similar examples have been found in the fossil record of plant galls and leaf mines. For example, there are species of wasps, called inquilines, which are unable to induce their own plant galls, so they simply take up residence in the galls that are made by other wasps. [19] Another example is the predation of plant galls or leaf mines, to eat the trapped insect larva inside the gall or mine. [50]
Studies of parasite remains and traces from the past have yielded a vast catalog of ancient host-parasite associations. [10] [51] [52] [53] Genetic sequence data obtained directly from ancient animal parasites, [54] and inferences of past relationships based on genetic sequences of existing parasite groups are also being applied to paleoparasitological questions. [55] [56] Data obtained by all of these methods are constantly improving our understanding of the origin and evolution of the parasites themselves [57] and their vectors, [58] and of the host-parasite and vector-parasite associations. [59] [60] [61] [62] [63]
In some cases, presumed host-parasite relationships of the past seem quite different from those known in the present, such as a fly which appears to be a parasite of a mite [64]
Paleoparasitological studies have also provided insight into questions outside the realm of parasitology. Examples include the migration and phylogeography of marine mammal hosts, [65] the identity of domestic animal bones based on the known hosts of parasite remains found at the site, [66] and the possible role of climatic changes on animal host genetic diversity. [67]
Mosquitoes, the Culicidae, are a family of small flies consisting of 3,600 species. The word mosquito is Spanish and Portuguese for little fly. Mosquitoes have a slender segmented body, one pair of wings, three pairs of long hair-like legs, and specialized, highly elongated, piercing-sucking mouthparts. All mosquitoes drink nectar from flowers; females of some species have in addition adapted to drink blood. Evolutionary biologists view mosquitoes as micropredators, small animals that parasitise larger ones by drinking their blood without immediately killing them. Medical parasitologists view mosquitoes instead as vectors of disease, carrying protozoan parasites or bacterial or viral pathogens from one host to another.
Nematomorpha are a phylum of parasitoid animals superficially similar to nematode worms in morphology, hence the name. Most species range in size from 50 to 100 millimetres, reaching 2 metres (79 in) in extreme cases, and 1 to 3 millimetres in diameter. Horsehair worms can be discovered in damp areas, such as watering troughs, swimming pools, streams, puddles, and cisterns. The adult worms are free-living, but the larvae are parasitic on arthropods, such as beetles, cockroaches, mantises, orthopterans, and crustaceans. About 351 freshwater species are known and a conservative estimate suggests that there may be about 2000 freshwater species worldwide. The name "Gordian" stems from the legendary Gordian knot. This relates to the fact that nematomorphs often coil themselves in tight balls that resemble knots.
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson characterised parasites as "predators that eat prey in units of less than one". Parasites include single-celled protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes.
Louse is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result of developments in phylogenetic research.
Trypanosomatida is a group of kinetoplastid unicellular organisms distinguished by having only a single flagellum. The name is derived from the Greek trypano (borer) and soma (body) because of the corkscrew-like motion of some trypanosomatid species. All members are exclusively parasitic, found primarily in insects. A few genera have life-cycles involving a secondary host, which may be a vertebrate, invertebrate or plant. These include several species that cause major diseases in humans. Some trypanosomatida are intracellular parasites, with the important exception of Trypanosoma brucei.
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist guest (symbiont). The guest is typically provided with nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring pathogenic (disease-causing) viruses, or a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.
In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasitism, distinguished by the fatal prognosis for the host, which makes the strategy close to predation.
Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question but by their way of life. This means it forms a synthesis of other disciplines, and draws on techniques from fields such as cell biology, bioinformatics, biochemistry, molecular biology, immunology, genetics, evolution and ecology.
The members of the Triatominae, a subfamily of the Reduviidae, are also known as conenose bugs, kissing bugs, or vampire bugs. Other local names for them used in the Americas include barbeiros, vinchucas, pitos, chipos and chinches. Most of the 130 or more species of this subfamily feed on vertebrate blood; a very small portion of species feed on invertebrates. They are mainly found and widespread in the Americas, with a few species present in Asia and Africa. These bugs usually share shelter with nesting vertebrates, from which they suck blood. In areas where Chagas disease occurs, all triatomine species are potential vectors of the Chagas disease parasite Trypanosoma cruzi, but only those species that are well adapted to living with humans are considered important vectors. Also, proteins released from their bites have been known to induce anaphylaxis in sensitive and sensitized individuals.
Dauer describes an alternative developmental stage of nematode worms, particularly rhabditids including Caenorhabditis elegans, whereby the larva goes into a type of stasis and can survive harsh conditions. Since the entrance of the dauer stage is dependent on environmental cues, it represents a classic and well studied example of polyphenism. The dauer state is given other names in the various types of nematodes such as ‘diapause’ or ‘hypobiosis’, but since the C. elegans nematode has become the most studied nematode, the term ‘dauer stage’ or 'dauer larvae' is becoming universally recognised when referring to this state in other free-living nematodes. The dauer stage is also considered to be equivalent to the infective stage of parasitic nematode larvae.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2004.
Archaeoparasitology, a multi-disciplinary field within paleopathology, is the study of parasites in archaeological contexts. It includes studies of the protozoan and metazoan parasites of humans in the past, as well as parasites which may have affected past human societies, such as those infesting domesticated animals.
Paleoleishmania is an extinct genus of kinetoplastids, a monophyletic group of unicellular parasitic flagellate protozoa. At present it is placed in the family Trypanosomatidae. The genus contains two species, the type species Paleoleishmania proterus and the later described Paleoleishmania neotropicum.
Heydenius is a collective group genus of fossil mermithid nematodes from the Tertiary period that cannot be placed in extant genera.
Allantonematidae is a family of insect-parasitic nematodes from the order Tylenchida. Allantonematid nematodes infect a variety of insects including beetles, butterflies, flies, thrips, ants, and more. For instance, the nematode Howardula aoronymphium parasitizes mushroom-feeding fruit flies, Formicitylenchus oregonensis parasitizes carpenter ants, and Metaparasitylenchus hypothenemi parasitizes a pest of coffee beans, the coffee berry borer.
2018 in paleoentomology is a list of new fossil insect taxa that were described during the year 2018, as well as other significant discoveries and events related to paleoentomology that were scheduled to occur during the year.
2019 in paleoentomology is a list of new fossil insect taxa that were described during the year 2019, as well as other significant discoveries and events related to paleoentomology that were scheduled to occur during the year.
2017 in paleoentomology is a list of new fossil insect taxa that were described during the year 2017, as well as other significant discoveries and events related to paleoentomology that were scheduled to occur during the year.
Burmese amber is fossil resin dating to the early Late Cretaceous Cenomanian age recovered from deposits in the Hukawng Valley of northern Myanmar. It is known for being one of the most diverse Cretaceous age amber paleobiotas, containing rich arthropod fossils, along with uncommon vertebrate fossils and even rare marine inclusions. A mostly complete list of all taxa described up until 2018 can be found in Ross 2018; its supplement Ross 2019b covers most of 2019.
2015 in paleoentomology is a list of new fossil insect taxa that were described during the year 2016, as well as other significant discoveries and events related to paleoentomology that were scheduled to occur during the year.
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