Somos mamíferas

Greetings to Somos Mamíferas!

Greetings to Somos Mamíferas! I’m María Sierra Kiekari, and I am delighted to extend a warm invitation for you to explore the depths of my heart and join me in a journey of sharing my voice, feelings, thoughts, and experiences through the “Somos Mamíferas” blog.

Today, on this meaningful journey, I want to delve into the essence of Somos Mamíferas, unraveling the intricacies of what defines us as mammals.

So, what sets a mammal apart as a mammal? And, on a personal note, we, human females and our fellow female mammals, fall under the category of placental mammals. Let’s explore some key characteristics that make us true mammals:

• All of us share the designation of vertebrates, boasting a vertebral column with an articulated skeleton of bones, our internal scaffolding.
• We are warm-blooded creatures, equipped with the remarkable ability to regulate our own temperature.
• Cloaked in hair, a defining feature that remains, even if we choose to shed it.
• We embrace the profound journey of nourishing our offspring with our own milk, a sacred elixir produced through the intricacies of mammary glands.

Yes, we are bearers of mammary glands, we mammals. Our offspring arrive in this world in diverse forms – some as sizable, well-formed fetuses, others as petite, undeveloped embryos. In parallel to our vertebrate counterparts, all female mammals possess ovaries, the cradle of life, producing the essential eggs.

Now, let’s dive into the realm of placental mammals. This broad category unfolds into placental mammals and marsupials, each crafting its unique reproductive narrative.

As female placental mammals, we stand united within this group. Our kinship includes the likes of whales, elephants, dogs, bats, shrews, armadillos, sheep, cows, and, of course, us, human females. Our roots trace back to a diminutive, fur-covered creature that once thrived on insects. According to research, this ancestral mammal lived either post-dinosaur extinction or side by side with these magnificent creatures. Picture it – this tiny creature already shared Earth with dinosaurs.

What captures my awe is the realization that our placental group spans over 5,000 species today. In essence, we are a vast and diverse collective of placental mammals, offering a tapestry of wisdom from which we can glean profound lessons. Within this extensive group, we encounter placental mammals soaring through the skies, gracefully swimming, swift runners, small and delicate creatures, monumental beings, and more.

So, what defines us as placental mammals? Placental mammals, much like us, bring forth offspring nurtured within the mother’s womb before birth. Thus, whether you once fed in your mother’s uterus or are currently gestating, your baby is savoring the nourishment in your womb through the sacred conduit of the placenta – an embryonic organ woven with care to sustain, nurture, and safeguard us.

While there exists a dichotomy between placental and marsupial mammals, it’s noteworthy that marsupials also possess a placenta. However, it’s the transient nature of the marsupial placenta that distinguishes it. The commitment to nourishing offspring is more robust in placental mammals. In marsupials, the offspring is birthed at an early stage and continues its development in the protective pouch – a realm familiar to kangaroos.

The birthing process for placental mammals begets larger and more mature offspring. Now, turning our gaze to the placenta – this sacred organ adorned with a spongy and membranous structure, brimming with rivers, the lifeblood vessels, connecting both mother and embryo.

The placenta assumes multifaceted roles in caring for offspring, for you, and for your progeny if you’re a mother or currently gestating. It serves as a respiratory organ, nourishing us through oxygen-rich rivers, a nutrition system bestowing substances vital for both mother and offspring.

Furthermore, the placenta plays the part of an excretory and cleansing organ, facilitating the passage of carbon dioxide and waste from the fetus to the mother. It is also an endocrine gland, producing hormones that cradle the life and health of both mother and baby. Elegantly, the placenta acts as our first boundary, enabling a seamless exchange of substances between the blood of the fetus and the mother without merging.

In essence, there is no fusion, but a sacred relationship – a differentiation of space, identity, and existence between the mother and the developing life within. The placenta, therefore, stands as a sentinel, shielding the fetus from the mother’s immune system, ensuring it remains unscathed and cared for.

Thanks to the placenta, we traverse an extensive period of growth in the womb – a journey made possible by this nurturing organ. It facilitates our growth and maturation before birth, equipping us to brave the world outside. In this way, the placenta becomes our guide, preparing us for the transition from the aqueous realm to the terrestrial abode.

Now, let’s turn our attention to marsupials. Although we may not be marsupials per se, there’s much we can glean from their unique experiences. A kinship emerges as we share certain traits, such as the profound sense of attachment, a hallmark of marsupials. Let me delve into this connection.

Marsupials harbor a placenta with a fleeting existence, as mentioned before. We, as human babies, share a similar narrative – born immature, reliant on the mother for survival, owing to our underdeveloped brains at birth. This underdevelopment serves a purpose, allowing us to traverse the birth canal.

Had our brains been fully mature, the journey through the birth canal would be arduous, especially considering the relative size of our heads to our bodies at birth. The initial years become a crucible for our brain’s maturation, an exponential growth from birth to adulthood, tripling or quadrupling in size.

Contrastingly, marsupials chart a different course in reproduction. A marsupial, also a therian mammal, gives birth to an early and immature embryo. This embryo completes its development outside the mother’s body, finding refuge in the marsupium – a pouch nestled in the mother’s belly. You may have witnessed this in kangaroos, koalas, or opossums – quintessential marsupials.

What resonates is the kinship between us, placental mammals, and marsupials. Like them, we cradle and hold our offspring close to our skin, close to our chest. The marsupial within us imparts a profound lesson on the significance of proximity and physical contact for offspring – a nurturing environment fostering health, growth, brain maturation, stress reduction, and, crucially, attachment.

Attachment, this emotional bond formed in the early years with caregivers – whether it be mom, dad, or other caretakers – leaves an indelible mark. Returning to the marsupial embryo, its nourishment within the mother’s uterus occurs through a yolk sac, a departure from our own reliance on the placenta.

In our embryonic journey, we too had a yolk sac, serving as our initial digestive system before the placenta assumed the role of nutrition. This yolk sac stockpiles enough sustenance for the brief period the marsupial embryo remains in the uterus. Once born, the embryo gravitates towards the marsupium, the pouch, where a nipple awaits. Within the pouch, the embryo latches onto the nipple, remaining sheltered for months, undergoing continuous growth and development.

Even as the offspring attains the size to venture beyond the pouch, it often returns, seeking warmth and sustenance. With time, maturation allows the offspring to stride independently. For those tuning in from Mexico – my current residence – the opossum is the indigenous marsupial. The female opossum cradles her babies, journeying with them wherever she goes.

Remarkably, the opossum is self-sufficient from gestation. Born after two weeks, weighing merely one gram, the opossum offspring autonomously navigates to the pouch. With adept claws, they cling to the nipple, sustaining themselves. Another category of mammals, not therian mammals, is called monotremes. Monotreme mammals lay eggs, with the platypus and echidnas being the sole living species, exclusive to Australia and New Guinea. While I won’t delve into monotreme mammals’ intricacies, it’s a facet worth noting.

In this exploration of our evolution as placental mammals, we unearth our roots, our origins, and identify our pack. Armed with this understanding, we can glean invaluable insights from the lives of whales, elephants, wolves, dogs, cats – each offering profound lessons on instinctual living and nurturing the pack.