30 May 2023

Literatuur bij het Skepter artikel Seks met aliens

Skepter Zomer 2023

In de Skepter zomer 2023 verscheen een kort artikel van mijn hand 'Seks met aliens'. Daarin onderzocht ik de mogelijkheid of buitenaardse wezens seks zouden kunnen hebben met mensen en nakomelingen zouden kunnen voortbrengen. Het was een spin-off van de bespreking van het boek van Erich von Daniken 'Evolution is Wrong' op mijn WDW website. Omdat ik maar beperkte ruimte had moest ik veel interessante argumenten weglaten en kon ik geen literatuurlijst geven. Hieronder volgt een lijst die ik de komende tijd zal aanvullen.

Literature about the possibility of sex with aliens.

  updated 9 Jun 2023

In the summer edition of Skepter an article (Dutch) by myself appeared about the possibility of aliens having sex with humans. The magazine is published by the Dutch Skeptics society. The article is a spin-off of the review of Erich von Daniken 'Evolution is Wrong'. According to von Daniken "There were and there are genetic interventions conducted by aliens in humans." Because the size restrictions of the article I could not include many interesting arguments and literature. Here I give a literature list which I will update in the coming weeks.

It appears that their are many obstacles to human-alien hybridization despite the fact that physical and biochemical laws are truly universal. Interestingly, the obstacles are caused by unique historical evolutionary events that happened during the evolution of life on planet earth. Those accidental features create an insurmountable barrière to hybridization.

  • Humans: Human Genome and Human chromosomes.
  • Chromosome numbers: List of organisms by chromosome count shows huge variation in chromosome number of organisms on planet earth.
  • Genetic Code: Genetic Code (universal genetic code) including Alternative genetic codes. The Vertebrate mitochondrial code (including humans) has 4 different codes compared to the Universal Genetic Code. In the evolutionary past many genes from the original mitochondrion migrated to the nucleus and only 37 genes remained in mitochondrial DNA  (a unique historical process).
  • Sex chromosomes: Y-chromsome, and The Incredible Shrinking Sex Chromosome, the Y-chromosome has its own unique history.
  • Non-standard chromosome number in healthy humans: Robertsonian translocation with a human with 2n=44. 
  • Pairing of homologous chromosomes in meiosis (Synaptonemal complex) is only possible between a chromosome from the father and the homologous chromosome from the mother. If the father is an alien, pairing will fail because there will be no homologous chromosomes at all, consequently the hypothetical hybrid is sterile.
  • An unusually knowledgeable Wikipedia page about hybidization between humans and non-humans.
  • Biological species are separated by reproductive barriers. A species is a group of organisms in which any two individuals of the appropriate sexes can produce fertile offspring.
  • Sex organs of alien and human must match (anatomy, physiology, endocrinology). Sperm must find its way to the egg cell, see: How sperm find their way.
  • Fertility problems are expected to be a reproductive barrier between humans and aliens. Infertility in the humans species has become a major issue for human reproductive health and affects up to one in seven couples worldwide. That is 14% of couples experience fertility problems. Estimates from 1997 suggest that worldwide about five percent of all heterosexual couples have an unresolved problem with infertility (wikipedia). And that is within the human species. See: Understanding the genetics of human infertility, Science, 13 Apr 2023. 
  • Genetic incompatibility: Genetic incompatibility of the reproductive partners: an evolutionary perspective on infertility, Human Reproduction, 2021  (Open Access) is about the human species. One problem is that natural fertilisation success is heavily dependent on the ability of sperm to traverse the female reproductive tract in the vicinity of an unfertilised oocyte. Sperm are directed towards the chemical factors secreted by unfertilised oocytes. Those factors must match.
  • Non-matching paternal and maternal epigenetic imprinting of genes active during pregnancy can cause either suboptimal or superoptimal growth of the fetus.  Wikipedia: Genomic imprinting. 25 jul 2023.
  • Human Sperm Plasma Allergyan immunological reaction against human seminal plasma observed in young women. When untreated this could be live-threatening. The cause is a protein in the semen. Likely, Alien sperm is expected to be a high risk for developing HSPA. (Wikipedia), (other source) 11 Jul 2023.
  • Immune system: pathogens have significantly altered the human genome. This topic has not been included in the Skepter article. The idea is that past pandemics have shaped the human genome and those pathogens and genomic changes are unique for life on earth. Alien beings will not have experienced the same pathogens and consequently those pathogens could be lethal to aliens. Also, hypothetical human-alien hybrids likely will suffer immunological problems.
  • Immunological incompatibility (pregnancy):  When pregnant, maternal immunologic tolerance is required to ensure that the (alien!) fetus is not "rejected" by the mother’s immune system. 22 Sep 2023
  • Biochemistry: here is a nice overview of Hypothetical types of biochemistry on Wikipedia (including hypothetical Silicon-based life). 




  • Wallace Arthur (2023) 'Understanding Life in the Universe', Cambridge University Press; New edition. Paperback 150 pages. This is a short and useful introduction to astrobiology by an evolutionary biologist who wrote several other books on evolution and astrobiology. See also my introduction to Astrobiology page on my WDW website. 
  • Stephen Freeland (2008) Fitness of the cosmos for life, chapter 14, page 301 about the Universal Genetic Code. 
  • Erich von Daniken (2022)  'Evolution is Wrong' (see my review).
  • Bill Chalker (2005) Hair of the Alien: DNA and Other Forensic Evidence of Alien Abductions, Gallery Books. One of the rare instances that a DNA analysis is done on a hair of an 'alien'. 
  • Albert E. Potts (2021) Genetic Genesis: DNA Manipulation of Our Ancient Ancestors From the Original Biblical Text. Info van de uitgever: "Detailed descriptions of alien creation of Homo sapiens through advanced DNA technologies, in vitro fertilization (IVF), and interspecies sexual experimentation." Daar heb je het weer: kruising tussen mens en aliens. [29 Feb 2024]

18 May 2023

This morning I found a dead House Sparrow (huismus) at my doorstep

Dead House Sparrow
Passer domesticus


On the morning of Ascension Day I found a dead male House Sparrow at my doorstep. Death is inevitable. Death is part of the natural cycle of life. So House Sparrows must die one day too, or so to speak go to heaven. But, I have never seen a dead House Sparrow, certainly not at my doorstep. What happened? What is the cause of death? Old age? A cat? Attacked by a bird of prey? Flew into a window? Sick? A virus infection? Why precisely at my doorstep? I couldn't see any blood or damage. The cause of death remains a mystery! He doesn't belong in the garbage bin, so we respectfully buried the bird in our garden. That too is part of the natural cycle of life. He was part of a group of house sparrows daily visiting our garden to search for breadcrumbs. The other group members seem to be happy as always. I enjoy their company every day.

14 May 2023

House Sparrow mother feeding cute infant. Huismusmoeder voert bedelend jong.

House Sparrow mother feeding cute, hungry infant

Location: The Netherlands. May 11 2023

The House Sparrow / Huismus / Passer domesticus is nr 1 on the list of most common garden birds in the Netherlands. It typically can be found in villages, towns, farms but not in forests and woods. Although they are number 1 in gardens, 30 years ago their numbers started to decline due to lack of nesting places (better isolation of houses). They now depend nearly completely on nesting boxes provided by humans. Also feeding is important. 

Stray cats who catch inexperienced young birds despite being fed by their owners are a threat. 

House Sparrows are a social animal and live always in groups. In this video we see the typical begging behavior with vibrating wings of young birds. I haven't seen fathers feeding the young. Not yet...

The 'Eurasian Tree Sparrow' (Passer montanus / Ringmus ) is the only other species of the genus Passer that can be observed as a breeding bird in The Netherlands. It is less common and is not 'domesticated' to the same degree.


03 May 2023

Western jackdaw with white feathers. Kauw met witte veren. Coloeus monedula. Leucism.

***Updated 15 June***


Western jackdaw with white feathers
Kauw met witte veren
7 April 2023 The Netherlands ©Gert Korthof

A Western jackdaw ( Coloeus monedula ) with white feathers is rare. It is a mutation in the melanin pigment producing cells in the feathers. For the first time this individual visited our garden and I could make a reasonable good portrait. This individual has been spotted at least the previous year at other locations nearby together with members of his own species. Apparently accepted as a member of the group. It seems to be a healthy and otherwise normal Jackdaw.

same individual. 7 April 2023. ©Gert Korthof

Some 5 weeks later, on 15 June, I observed the 'white' jackdaw again on a chimney with a 'normal' partner:

15 June 2023 ©Gert Korthof

15 June 2023 ©Gert Korthof

Many Jackdaws here use the chimneys as nesting places. So, maybe the 'white' and the 'normal' Jackdaw are going to produce young Jackdaws... How will they look like?

= = =

I found  many other pictures on the internet. Keep in mind that rare birds have a higher probability of being published! The more I searched the more I found!

Wikipedia Western jackdaw:

By Markus Rantala (Makele-90) - Own work, CC BY-SA 3.0

These birds have seemingly random white spots and patches:

Vroege Vogels: Kauw in het wit (2016)

Pied Jackdaw (flickr)

Magnificent leucistic jackdaw (Linda)
random white spots and patches

Nice picture by ©Linda

To me it looks like a Nordic Jackdaw subspecies (Noordse Kauw)

Kauw, afwijkend (waarneming.nl 2006)

Darley Dale Wildlife: Partially albino Jackdaw
Andy Butler http://darleydalewildlife.blogspot.com

'Partial albino' is not a correct description. Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and reddish pink or blue eyes. So, this is a leucistic Jackdaw because it clearly has black pigment.


White and black Jackdaw together ( BBC )
BBC - Avebury's rare albino faces black future

Please note that the following bird looks like a leucistic Jackdaw:

Daurian Jackdaw (Coloeus dauuricus) (Dmitry Dubikovskiy)

but do not get confused, the above picture is the Daurian Jackdaw, a geographic species of the Coloeus genus.

The Hooded Crow (Corvus cornix) is not a leucistic crow but it is the normal color pattern of the species:

Hooded Crow, Bonte Kraai ( Jeanne Kliemesch )

At the Corvid Research blog I found a blogpost about leucism in general with some pictures of leucistic Jackdaws in flight. Corvidae is the family name which includes Eurasian magpie, Common raven, Carrion crow.

Here is a story at the Garden Wildlife Health  website about leucism with pictures.

The British Trust for Ornithology writes that leucism is heritable, but I think this is not always the case. When the mutation happens after fertilization, thus during development of the embryo, it is a somatic mutation, and does not occur in the germline. So, is not heritable.

Finally, a video with a very rare and amazing White Blackbird:

Leucistic Blackbird video (A Shot Of Wildlife)


Last but not least: an extreme form of Jackdaw leucism:

Jackdaw extreme leucism! ( flickr )

Automatic species identification software:

The most amazing fact: the rare white blackbird is recognized by ObsIdentify-NIA as a Blackbird with 97%! How on earth is he doing that? Interestingly, all the other leucistic Jackdaws are identified by ObsIdentify-NIA with 99%-100% certainty as a Western Jackdaw except the picture by Fredrik Grahn which is identified as a Nordic Jackdaw (Noordse Kauw) with 100% certainty. The Noridc Jackdaw is considered a subspecies: Western Jackdaw ssp monedula. The software is able to identify the Jackdaw despite the white feathers: how does he do it? [ 6 May ]

Further Reading